Luminescent 1-hydroxy-2-pyridinone chelates of lanthanides

ABSTRACT

The present invention provides luminescent complexes between a lanthanide ion and an organic ligand which contains 1,2-hydroxypyridinone units. The complexes of the invention are stable in aqueous solutions and are useful as molecular probes, for example in medical diagnostics and bioanalytical assay systems. The invention also provides methods of using the complexes of the invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.12/373,275, filed Aug. 14, 2009, which is a National Stage Entry ofInternational Application No. PCT/US2007/073185, filed Jul. 10, 2007,which claims priority from U.S. Provisional Patent Application No.60/819,904, filed Jul. 10, 2006, all of which are incorporated herein byreference in their entirety for all purposes.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH AND DEVELOPMENT

This invention was made with government support under Grant NumbersHL069832 and DK057814 awarded by the National Institutes of Health andContract Number DE-AC3-76SF00098 awarded by the Department of Energy.The government has certain rights in the invention.

FIELD OF THE INVENTION

This invention relates to lanthanide complexes, useful as luminescentmarkers, as well as methods utilizing the complexes of the invention.

BACKGROUND OF THE INVENTION

Luminescent metal complexes are valuable as probes and labels in avariety of applications such as diagnostic products and bioanalyticalassay systems.

There is a continuing and expanding need for rapid, highly specificmethods of detecting and quantifying chemical, biochemical andbiological substances as analytes in research and diagnostic mixtures.Of particular value are methods for measuring small quantities ofproteins, nucleic acids, peptides, pharmaceuticals, metabolites,microorganisms and other materials of diagnostic value. Examples of suchmaterials include small molecular bioactive materials (e.g., narcoticsand poisons, drugs administered for therapeutic purposes, hormones),pathogenic microorganisms and viruses, antibodies, and enzymes andnucleic acids, particularly those implicated in disease states.

The presence of a particular analyte can often be determined by bindingmethods that exploit the high degree of specificity, which characterizesmany biochemical and biological systems. Frequently used methods arebased on, for example, antigen-antibody systems, nucleic acidhybridization techniques, and protein-ligand systems. In these methods,the existence of a complex of diagnostic value is typically indicated bythe presence or absence of an observable “label” which has been attachedto one or more of the interacting materials. The specific labelingmethod chosen often dictates the usefulness and versatility of aparticular system for detecting an analyte of interest. Preferred labelsare inexpensive, safe, and capable of being attached efficiently to awide variety of chemical, biochemical, and biological materials withoutsignificantly altering the important binding characteristics of thosematerials. The label should give a highly characteristic signal, andshould be rarely, and preferably never, found in nature. The labelshould be stable and detectable in aqueous systems over periods of timeranging up to months. Detection of the label is preferably rapid,sensitive, and reproducible without the need for expensive, specializedfacilities or the need for special precautions to protect personnel.Quantification of the label is preferably relatively independent ofvariables such as temperature and the composition of the mixture to beassayed.

A wide variety of labels have been developed, each with particularadvantages and disadvantages. For example, radioactive labels are quiteversatile, and can be detected at very low concentrations, such labelsare, however, expensive, hazardous, and their use requires sophisticatedequipment and trained personnel. Thus, there is wide interest innon-radioactive labels, particularly in labels that are observable byspectrophotometric, spin resonance, and luminescence techniques, andreactive materials, such as enzymes that produce such molecules.

Labels that are detectable using fluorescence spectroscopy are ofparticular interest, because of the large number of such labels that areknown in the art. Moreover, the literature is replete with syntheses offluorescent labels that are derivatized to allow their facile attachmentto other molecules, and many such fluorescent labels are commerciallyavailable.

In addition to being directly detected, many fluorescent labels operateto quench or amplify the fluorescence of an adjacent second fluorescentlabel. Because of its dependence on the distance and the magnitude ofthe interaction between the quencher and the fluorophore, the quenchingof a fluorescent species provides a sensitive probe of molecularconformation and binding, or other, interactions. An excellent exampleof the use of fluorescent reporter quencher pairs is found in thedetection and analysis of nucleic acids.

An alternative detection scheme, which is theoretically more sensitivethan autoradiography, is time-resolved fluorimetry. According to thismethod, a chelated lanthanide metal with a long radiative lifetime isattached to a molecule of interest. Pulsed excitation combined with agated detection system allows for effective discrimination againstshort-lived background emission. For example, using this approach, thedetection and quantification of DNA hybrids via an europium-labeledantibody has been demonstrated (Syvanen et al., Nucleic Acids Research14: 1017-1028 (1986)). In addition, biotinylated DNA was measured inmicrotiter wells using Eu-labeled streptavidin (Dahlen, Anal. Biochem,164: 78-83 (1982)). A disadvantage, however, of these types of assays isthat the label must be washed from the probe and its fluorescencedeveloped in an enhancement solution. A further drawback has been thefact that the fluorescence produced has only been in the nanosecond (ns)range, a generally unacceptably short period for adequate detection ofthe labeled molecules and for discrimination from backgroundfluorescence.

In view of the predictable practical advantages it has been generallydesired that the lanthanide chelates employed should exhibit a delayedluminescence with decay times of more than 10 μs. The fluorescence ofmany of the known fluorescent chelates tends to be inhibited by waterand require augmentation with e.g. fluoride or micelles. As water isgenerally present in an assay, particularly an immunoassay system,lanthanide complexes that undergo inhibition of fluorescence in thepresence of water are viewed as somewhat unfavorable or impractical formany applications. Moreover, the short fluorescence decay times isconsidered a disadvantage of these compounds. This inhibition is due tothe affinity of the lanthanide ions for coordinating water molecules.When the lanthanide ion has coordinated water molecules, the absorbedlight energy (excitation energy) is transferred from the complex to thesolvent rather than being emitted as fluorescence.

Thus, stable lanthanide chelates, particularly coordinatively saturatedchelates having excellent luminescence properties are highly desirable.In the alternative, coordinatively unsaturated lanthanide chelates thatexhibit acceptable luminescence in the presence of water are alsoadvantageous. Such chelates that are derivatized to allow theirconjugation to one or more components of an assay, find use in a rangeof different assay formats. The present invention provides these andother such compounds and assays using these compounds.

Derivatives of 1-hydroxy-2-pyridinone (Structure 1) are of particularinterest, since the ligand and its mono-anion (Structure 2) have azwitterionic resonance form (Structure 3) that is isoelectronic with thecatechol dianion.

Further, the 1-hydroxy-2-pyridinone structure possesses syntheticadvantages, since the 6-carboxylic acid derivative (Structure 4) can bemade in a straightforward manner.

Since the 1,2-HOPO ligands are useful sequestering agents for hard metalions, especially for the f-elements, effort has been directed towardsimproving the initial synthesis of complexing ligands based on 1,2-HOPO.The original synthesis of multidentate 1,2-HOPO ligands, reported adecade ago, involves several low yield steps, difficult purificationsand the use of phosgene (White et al., J. Med. Chem. 31: 11-18 (1988).The use of phosgene gas is undesirable for a number of reasons: theprocedure is tedious; phosgene is highly toxic and volatile; the yieldof the amine conjugate is low (e.g., yields of 3,4-LI-1,2-HOPO, and3,4,3-LI-1,2-HOPO using phosgene were 34% and 15%, respectively); andthe separation of the resulting product is difficult, often requiringthe use of HPLC.

Uhlir reported that, following benzyl protection of the N-hydroxyl groupof 6-carboxy-1,2-HOPO, this protected species could be activated andcoupled to an amine scaffold (Uhlir, L. C. MIXED FUNCTIONALITY ACTINIDESEQUESTERING AGENTS. Ph.D. thesis, University of California, Berkeley,1992). Uhlir activated the HOPO carboxyl group using NHS/DCC andHOBT/DCC (see, Bodansky, M.; Bodanszky, A., THE PRACTICE OF PEPTIDESYNTHESIS 2nd Ed., Springer-Verlag Berlin Heidelberg 1994, pp 96-125).Uhlir did not disclose the formation of an acid halide from the benzylprotected HOPO derivative.

Bailly et al. reported the multistep preparation of a benzyl protected1,2-HOPO acid chloride and the use of the protected acid chloride toform amine conjugates of 1,2-HOPO (C. R. Acad. Sci. Paris 1, Serie II:241-245 (1998)). The procedure of Bailly et al. is cumbersome, requiringconversion of the carboxylic acid to the corresponding methyl ester,activation and protection of the N-hydroxyl group, saponification of themethyl ester, followed by the activation of the carboxylic acid as theacid chloride. Bailly et al. does not suggest that the hydroxyl groupcan be protected in the presence of the free acid at the 6-position.

Other related art includes U.S. Pat. No. 4,698,431, which disclosespolyvalent 1,2-HOPO chelators having an amide or a carboxylic acidmoiety in the 6-position. The chelating agents are useful in selectivelyremoving certain cations from solution and are particularly useful asferric ion and actinide chelators. U.S. Pat. No. 5,892,029 and U.S. Pat.No. 5,624,901 also set forth polyvalent 1,2-HOPO chelators. None of thepatents discloses or suggests preparing a polyvalent chelator from aprotected, acid halide intermediate.

U.S. Pat. No. 4,666,927, discloses a number of chelating agents having1,2-HOPO, 3,2-HOPO, or 3,4-HOPO moieties incorporated within theirstructures that are linked through a number of possible combinations oflinking groups, including —CONH— groups. However, U.S. Pat. No.4,666,927 teaches against a HOPO moiety having a substitution ortho tothe hydroxy or oxo group of the HOPO ring, and does not disclose orsuggest an acyl halide 1,2-HOPO intermediate.

A need for luminescent complexes, which are stable under biologicalrelevant conditions and at low concentrations, remains. The currentinvention addresses these and other needs.

BRIEF SUMMARY OF THE INVENTION

The present invention is directed toward new classes of chelating agentsand metal complexes formed with these chelating agents. The invention isexemplified by reference to the use of the chelating agents to complexlanthanide metal ions, particularly those lanthanide ions, which, whencomplexed by a chelating agent of the invention form a luminescentlanthanide chelate. The luminescent metal chelates incorporating apyridinone, particularly a hydroxy-pyridinone subunit. An exemplaryhydroxy-pyridinone subunit is 1-hydroxy-2-pyridinone. The inventionprovides luminescent complexes formed between lanthanides, e.g., Tb⁺³and Eu⁺³, and organic ligands that incorporate 1-hydroxy-2-pyridinonesubunits as chelating agents. Also provided are complexes formed betweenactinides (e.g., ions of elements 89-103) and a chelating agent of theinvention.

Luminescent (including fluorescent, phosphorescent and emission arisingfrom metal ions) markers find a wide variety of applications in science,medicine and engineering. In many situations, these markers or probesprovide competitive replacements for radiolabels, chromogens,radiation-dense dyes, etc. Moreover, improvements in fluorometricinstrumentation have increased attainable sensitivities and permittedquantitative analysis.

Lanthanide chelates in combination with time-resolved fluorescentspectroscopy is a widely used analytical, e.g., immunochemical tool.Lanthanide ions generally utilized in analytical procedures includeDy³⁺, Sm³⁺, Tb³⁺, Er³⁺ and Eu³⁺, Nd³⁺, Tm³⁺, Yb³⁺. Other lanthanideions, such as La³⁺, Gd³⁺ and Lu³⁺ are useful as well.

The present invention provides luminescent lanthanide complexes thatpossess many features desired for luminescent markers and probes of usein fluorescent assay systems. Among these advantages are: 1) ligandsacting as both chelators and chromophore/energy transfer devices; 2)high quantum yields of lanthanide ion luminescence of the presentcomplexes in water without external augmentation, such as by micelles orfluoride; 3) high stability and solubility of these complexes in water;4) straight forward syntheses employing inexpensive starting materials;and 5) facile access to many derivatives for linking these luminescentprobes to, for example, an immunoreactive agent or solid support (e.g.,polymer).

Unexpectedly, the inventors have discovered that chelates formed betweena lanthanide ion and one or more organic ligands, incorporating a1-hydroxy-2-pyridinone (1,2-HOPO) subunit, are luminescent and exhibitsuperior stability in aqueous solutions, including those with low pH.Moreover, these ligands complex actinides to form highly stable actinideion complexes.

Thus, in one aspect, the invention provides a luminescent complexbetween a lanthanide ion and an organic ligand comprising the subunit ofFormula I:

wherein R¹, R², R³ and R⁴ are members independently selected from H, anaryl group substituent defined herein, a linker to a scaffold moiety anda linker to a functional moiety. M⁺³ is a metal ion, e.g., an actinideion or a lanthanide ion, preferably forming the luminescent complex withone or more organic ligands.

Other objects and advantages of the present invention are apparent fromthe detailed description below.

DETAILED DESCRIPTION OF THE INVENTION 1. Introduction

The present invention provides a class of chelating agents of use tochelate metal ions, e.g., actinides and lanthanides, and areparticularly preferred to form luminescent probes. The chelating agentsof the invention are based on 1,2-hydroxypyridinone-based ligands(“1,2-HOPO”). Exemplary chelating agents (and metal ion complexes) ofthe invention include 1,2-HOPO and other chelating moieties, e.g.,maltol derivatives, hydroxypyrimidinone (HOPY) derivatives,hydroxy-iso-phthalic acid derivatives, catecholic acid derivatives,terephthalic acid derivatives (e.g., terephthalamidyl, TAM) andsalicylic acid derivatives, preferably incorporated into a single ligandin which the subunits are linked by a scaffold moiety, e.g.,tris(2-aminoethyl)amine (TREN) and, preferably octadentate topologyscaffolds, such as H22.

Selected complexes of the invention emit light or they can be used toabsorb light emitted by a reporter fluorophore. The fluorophores of theinvention can be used as small molecules in solution assays or they canbe utilized as a label that is attached to an analyte or a species thatinteracts with, and allows detection and/or quantification of ananalyte.

Luminescent (e.g., fluorescent) labels have the advantage of requiringfew precautions in their handling, and being amenable to high-throughputvisualization techniques (optical analysis including digitization of theimage for analysis in an integrated system comprising a computer).Preferred labels are typically characterized by high sensitivity, highstability, low background, long lifetimes, low environmental sensitivityand high specificity in labeling.

The fluorophores of the invention can also be used in conjunction withother fluorophores or quenchers as components of energy transfer probes.Many fluorescent labels are useful in combination with the chelators ofthe invention. Many such labels are commercially available from, forexample, the SIGMA chemical company (Saint Louis, Mo.), Molecular Probes(Eugene, Oreg.), R&D systems (Minneapolis, Minn.), Pharmacia LKBBiotechnology (Piscataway, N.J.), CLONTECH Laboratories, Inc. (PaloAlto, Calif.), Chem Genes Corp., Aldrich Chemical Company (Milwaukee,Wis.), Glen Research, Inc., GIBCO BRL Life Technologies, Inc.(Gaithersburg, Md.), Fluka Chemica-Biochemika Analytika (Fluka ChemieAG, Buchs, Switzerland), and Applied Biosystems (Foster City, Calif.),as well as many other commercial sources known to one of skill.Furthermore, those of skill in the art will recognize how to select anappropriate fluorophore for a particular application and, if not readilyavailable commercially, will be able to synthesize the necessaryfluorophore de novo or synthetically modify commercially availablefluorescent compounds to arrive at the desired fluorescent label.

In addition to small molecule fluorophores, naturally occurringfluorescent proteins and engineered analogues of such proteins areuseful with the complexes of the present invention. Such proteinsinclude, for example, green fluorescent proteins of cnidarians (Ward etal., Photochem. Photobiol. 35:803-808 (1982); Levine et al., Comp.Biochem. Physiol., 72B:77-85 (1982)), yellow fluorescent protein fromVibrio fischeri strain (Baldwin et al., Biochemistry 29:5509-15 (1990)),Peridinin-chlorophyll from the dinoflagellate Symbiodinium sp. (Morriset al., Plant Molecular Biology 24:673:77 (1994)), phycobiliproteinsfrom marine cyanobacteria, such as Synechococcus, e.g., phycoerythrinand phycocyanin (Wilbanks et al., J. Biol. Chem. 268:1226-35 (1993)),and the like.

The compounds of the invention can be used as probes, as tools forseparating particular ions from other solutes, as probes in microscopy,enzymology, clinical chemistry, molecular biology and medicine. Thecompounds of the invention are also useful as therapeutic agents inmodalities, such as photodynamic therapy and as diagnostic agents inimaging methods. Moreover, the compounds of the invention are useful ascomponents of optical amplifiers of light, waveguides and the like.Furthermore, the compounds of the invention can be incorporated intoinks and dyes, such as those used in the printing of currency or othernegotiable instruments.

The complexes of the invention emit fluorescence upon excitation usingany manner known in the art, including, for example, with light orelectrochemical energy (see, for example, Kulmala et al, AnalyticaChimica Acta 386: 1 (1999)). The luminescence can, in the case of chiralcompounds of the invention, be circularly polarized (see, for example,Riehl et al., Chem. Rev. 86: 1 (1986)).

The chelating agents and their metal ion complexes, e.g., luminescentcomplexes, and methods discussed in the following sections are generallyrepresentative of the compositions of the invention and the methods inwhich such compositions can be used. Many of the chelating agents areshown in the sections that follow in their complexed form (e.g.,complexed with M⁺³). These formulae are not limited to the metal ioncomplexes, but merely recite one form of the chelating agent, i.e.,complexed. The formulae are equally representative of the uncomplexedchelating agents, unless the chelating agent is designated as beingcomplexed with a specific metal ion or as having a specific propertyimparted to the complex by chelation of the metal ion (e.g.,luminescence). The following discussion is intended as illustrative ofselected aspects and embodiments of the present invention and it shouldnot be interpreted as limiting the scope of the present invention.

2. Definitions

Unless defined otherwise, all technical and scientific terms used hereingenerally have the same meaning as commonly understood by one ofordinary skill in the art to which this invention belongs. Generally,the nomenclature used herein and the laboratory procedures in molecularbiology, organic chemistry and nucleic acid chemistry and hybridizationdescribed below are those well known and commonly employed in the art.Standard techniques are used for nucleic acid and peptide synthesis. Thenomenclature used herein and the laboratory procedures in analyticalchemistry, and organic synthetic described below are those known andemployed in the art. Standard techniques, or modifications thereof, areused for chemical syntheses and chemical analyses.

“Analyte”, as used herein, means any compound or molecule of interestfor which a diagnostic test is performed, such as a biopolymer or asmall molecular bioactive material. An analyte can be, for example, aprotein, peptide, a lipid, a carbohydrate, polysaccharide, glycoprotein,hormone, receptor, antigen, antibody, virus, substrate, metabolite,transition state analog, cofactor, inhibitor, drug, dye, nutrient,growth factor, lipid etc., without limitation.

As used herein, “energy transfer” refers to the process by which thelight emission of a luminescent group is altered by aluminescence-modifying group. When the luminescence-modifying group is aquenching group then the light emission from the luminescent group isattenuated (quenched). Energy transfer mechanisms include luminescenceresonance energy transfer by dipole-dipole interaction (e.g., in longerrange energy transfer) or electron transfer (e.g., across shorterdistances). While energy transfer is often based on spectral overlappingof the emission spectrum of the luminescent group and the absorptionspectrum of the luminescence-modifying group, (in addition to distancebetween the groups) it has been demonstrated that spectral overlap isnot necessarily required for energy transfer to occur (see e.g., Latvaet al., U.S. Pat. No. 5,998,146, which is incorporated by reference inits entirety). It is to be understood that any reference to “energytransfer” in the instant application encompasses allmechanistically-distinct phenomena.

“Energy transfer pair” is used to refer to a group of molecules thatparticipate in energy transfer. Such complexes may comprise, forexample, two luminescent groups, which may be different from one-anotherand one quenching group, two quenching groups and one luminescent group,or multiple luminescent groups and multiple quenching groups. In caseswhere there are multiple luminescent groups and/or multiple quenchinggroups, the individual groups may be different from one another.Typically, one of the molecules acts as a luminescent group, and anotheracts as a luminescence-modifying group. The preferred energy transferpair of the invention comprises a luminescent group and a quenchinggroup of the invention. There is no limitation on the identity of theindividual members of the energy transfer pair in this application. Allthat is required is that the spectroscopic properties of the energytransfer pair as a whole change in some measurable way if the distancebetween the individual members is altered by some critical amount.

As used herein, “luminescence-modifying group” refers to a molecule ofthe invention that can alter in any way the luminescence emission from aluminescent group. A luminescence-modifying group generally accomplishesthis through an energy transfer mechanism. Depending on the identity ofthe luminescence-modifying group, the luminescence emission can undergoa number of alterations, including, but not limited to, attenuation,complete quenching, enhancement, a shift in wavelength, a shift inpolarity, and a change in luminescence lifetime. One example of aluminescence-modifying group is a fluorescence-modifying group. Anotherexemplary luminescence-modifying group is a quenching group.

As used herein, “quenching group” refers to any luminescence-modifyinggroup of the invention that can attenuate at least partly the lightemitted by a luminescent group. This attenuation is referred to hereinas “quenching”. Hence, excitation of the luminescent group in thepresence of the quenching group leads to an emission signal that is lessintense than expected, or even completely absent. Quenching typicallyoccurs through energy transfer between the luminescent group and thequenching group.

“Fluorescence resonance energy transfer” or “FRET” is usedinterchangeably with FET, and refers to an energy transfer phenomenon inwhich the light emitted by an excited fluorescent group is absorbed atleast partially by a fluorescence-modifying group of the invention. Ifthe fluorescence-modifying group is a quenching group, then that groupwill preferably not radiate a substantial fraction of the absorbed lightas light of a different wavelength, and will preferably dissipate it asheat. FRET depends on energy transfer between the fluorescent group andthe fluorescence-modifying group. FRET also depends on the distancebetween the quenching group and the fluorescent group.

“Moiety” refers to a radical of a molecule that is attached to anotherportion of the molecule.

As used herein, “nucleic acid” means DNA, RNA, single-stranded,double-stranded, or more highly aggregated hybridization motifs, and anychemical modifications thereof. Modifications include, but are notlimited to, those providing chemical groups that incorporate additionalcharge, polarizability, hydrogen bonding, electrostatic interaction, andfluxionality to the nucleic acid ligand bases or to the nucleic acidligand as a whole. Such modifications include, but are not limited to,peptide nucleic acids, phosphodiester group modifications (e.g.,phosphorothioates, methylphosphonates), 2′-position sugar modifications,5-position pyrimidine modifications, 8-position purine modifications,modifications at exocyclic amines, substitution of 4-thiouridine,substitution of 5-bromo or 5-iodo-uracil; backbone modifications,methylations, unusual base-pairing combinations such as the isobases,isocytidine and isoguanidine and the like. Modifications can alsoinclude 3′ and 5′ modifications such as capping with a fluorophore oranother moiety.

“Peptide” refers to a polymer in which the monomers are amino acids andare joined together through amide bonds, alternatively referred to as apolypeptide. When the amino acids are alpha-amino acids, either theL-optical isomer or the D-optical isomer can be used. Additionally,unnatural amino acids, for example, beta.-alanine, phenylglycine andhomoarginine are also included. Commonly encountered amino acids thatare not gene-encoded may also be used in the present invention. All ofthe amino acids used in the present invention may be either the D- orL-isomer. The L-isomers are generally preferred. The term “peptide” or“polypeptide”, as used herein, refers to naturally occurring as well assynthetic peptides. In addition, peptidomimetics are also useful in thepresent invention. For a general review, see, Spatola, A. F., inCHEMISTRY AND BIOCHEMISTRY OF AMINO ACIDS, PEPTIDES AND PROTEINS, B.Weinstein, eds., Marcel Dekker, New York, p. 267 (1983).

Where substituent groups are specified by their conventional chemicalformulae, written from left to right, they optionally equally encompassthe chemically identical substituents, which would result from writingthe structure from right to left, e.g., —CH₂O— is intended to alsorecite —OCH₂—.

The term “alkyl,” by itself or as part of another substituent, means,unless otherwise stated, a straight or branched chain, or cyclichydrocarbon radical, or combination thereof, which may be fullysaturated, mono- or polyunsaturated and can include di- and multivalentradicals, having the number of carbon atoms designated (i.e. C₁-C₁₀means one to ten carbons). Examples of saturated hydrocarbon radicalsinclude, but are not limited to, groups such as methyl, ethyl, n-propyl,isopropyl, n-butyl, t-butyl, isobutyl, sec-butyl, cyclohexyl,(cyclohexyl)methyl, cyclopropylmethyl, homologs and isomers of, forexample, n-pentyl, n-hexyl, n-heptyl, n-octyl, and the like. Anunsaturated alkyl group is one having one or more double bonds or triplebonds. Examples of unsaturated alkyl groups include, but are not limitedto, vinyl, 2-propenyl, crotyl, 2-isopentenyl, 2-(butadienyl),2,4-pentadienyl, 3-(1,4-pentadienyl), ethynyl, 1- and 3-propynyl,3-butynyl, and the higher homologs and isomers. The term “alkyl,” unlessotherwise noted, is also meant to include those derivatives of alkyldefined in more detail below, such as “heteroalkyl” with the differencethat the heteroalkyl group, in order to qualify as an alkyl group, islinked to the remainder of the molecule through a carbon atom. Alkylgroups that are limited to hydrocarbon groups are termed “homoalkyl”.

The term “alkenyl” by itself or as part of another substituent is usedin its conventional sense, and refers to a radical derived from analkene, as exemplified, but not limited by, substituted or unsubstitutedvinyl and substituted or unsubstituted propenyl. Typically, an alkenylgroup will have from 1 to 24 carbon atoms, with those groups having from1 to 10 carbon atoms being generally preferred.

The term “alkylene” by itself or as part of another substituent means adivalent radical derived from an alkane, as exemplified, but notlimited, by —CH₂CH₂CH₂CH₂—, and further includes those groups describedbelow as “heteroalkylene.” Typically, an alkyl (or alkylene) group willhave from 1 to 24 carbon atoms, with those groups having 10 or fewercarbon atoms being preferred in the present invention. A “lower alkyl”or “lower alkylene” is a shorter chain alkyl or alkylene group,generally having eight or fewer carbon atoms.

The terms “alkoxy,” “alkylamino” and “alkylthio” (or thioalkoxy) areused in their conventional sense, and refer to those alkyl groupsattached to the remainder of the molecule via an oxygen atom, an aminogroup, or a sulfur atom, respectively.

The term “heteroalkyl,” by itself or in combination with another term,means, unless otherwise stated, a stable straight or branched chain, orcyclic hydrocarbon radical, or combinations thereof, consisting of thestated number of carbon atoms and at least one heteroatom selected fromthe group consisting of O, N, Si and S, and wherein the nitrogen andsulfur atoms may optionally be oxidized and the nitrogen heteroatom mayoptionally be quaternized. The heteroatom(s) O, N and S and Si may beplaced at any interior position of the heteroalkyl group or at theposition at which the alkyl group is attached to the remainder of themolecule. Examples include, but are not limited to, —CH₂—CH₂—O—CH₃,—CH₂—CH₂—NH—CH₃, —CH₂—CH₂—N(CH₃)—CH₃, —CH₂—S—CH₂—CH₃, —CH₂—CH₂,—S(O)—CH₃, —CH₂—CH₂—S(O)₂—CH₃, —CH═CH—O—CH₃, —Si(CH₃)₃, —CH₂—CH═N—OCH₃,and —CH═CH—N(CH₃)—CH₃. Up to two heteroatoms may be consecutive, suchas, for example, —CH₂—NH—OCH₃ and —CH₂—O—Si(CH₃)₃. Similarly, the term“heteroalkylene” by itself or as part of another substituent means adivalent radical derived from heteroalkyl, as exemplified, but notlimited by, —CH₂—CH₂—S—CH₂—CH₂— and —CH₂—S—CH₂—CH₂—NH—CH₂—. Forheteroalkylene groups, heteroatoms can also occupy either or both of thechain termini (e.g., alkyleneoxy, alkylenedioxy, alkyleneamino,alkylenediamino, and the like). Still further, for alkylene andheteroalkylene linking groups, no orientation of the linking group isimplied by the direction in which the formula of the linking group iswritten. For example, the formula —CO₂R′— represents both —C(O)OR′ and—OC(O)R′.

The terms “cycloalkyl” and “heterocycloalkyl”, by themselves or incombination with other terms, represent, unless otherwise stated, cyclicversions of “alkyl” and “heteroalkyl”, respectively. Additionally, forheterocycloalkyl, a heteroatom can occupy the position at which theheterocycle is attached to the remainder of the molecule. A “cycloalkyl”or “heterocycloalkyl” substituent may be attached to the remainder ofthe molecule directly or through a linker, wherein the linker ispreferably alkylene. Examples of cycloalkyl include, but are not limitedto, cyclopentyl, cyclohexyl, 1-cyclohexenyl, 3-cyclohexenyl,cycloheptyl, and the like. Examples of heterocycloalkyl include, but arenot limited to, 1-(1,2,5,6-tetrahydropyridyl), 1-piperidinyl,2-piperidinyl, 3-piperidinyl, 4-morpholinyl, 3-morpholinyl,tetrahydrofuran-2-yl, tetrahydrofuran-3-yl, tetrahydrothien-2-yl,tetrahydrothien-3-yl, 1-piperazinyl, 2-piperazinyl, and the like.

The terms “halo” or “halogen,” by themselves or as part of anothersubstituent, mean, unless otherwise stated, a fluorine, chlorine,bromine, or iodine atom. Additionally, terms such as “haloalkyl,” aremeant to include monohaloalkyl and polyhaloalkyl. For example, the term“halo(C₁-C₄)alkyl” is mean to include, but not be limited to,trifluoromethyl, 2,2,2-trifluoroethyl, 4-chlorobutyl, 3-bromopropyl, andthe like.

The term “aryl” means, unless otherwise stated, a polyunsaturated,aromatic, substituent that can be a single ring or multiple rings(preferably from 1 to 3 rings), which are fused together or linkedcovalently. The term “heteroaryl” refers to aryl groups (or rings) thatcontain from one to four heteroatoms selected from N, O, S, Si and B,wherein the nitrogen and sulfur atoms are optionally oxidized, and thenitrogen atom(s) are optionally quaternized. A heteroaryl group can beattached to the remainder of the molecule through a heteroatom.Non-limiting examples of aryl and heteroaryl groups include phenyl,1-naphthyl, 2-naphthyl, 4-biphenyl, 1-pyrrolyl, 2-pyrrolyl, 3-pyrrolyl,3-pyrazolyl, 2-imidazolyl, 4-imidazolyl, pyrazinyl, 2-oxazolyl,4-oxazolyl, 2-phenyl-4-oxazolyl, 5-oxazolyl, 3-isoxazolyl, 4-isoxazolyl,5-isoxazolyl, 2-thiazolyl, 4-thiazolyl, 5-thiazolyl, 2-furyl, 3-furyl,2-thienyl, 3-thienyl, 2-pyridyl, 3-pyridyl, 4-pyridyl, 2-pyrimidyl,4-pyrimidyl, 5-benzothiazolyl, purinyl, 2-benzimidazolyl, 5-indolyl,1-isoquinolyl, 5-isoquinolyl, 2-quinoxalinyl, 5-quinoxalinyl,3-quinolyl, and 6-quinolyl. Substituents for each of the above notedaryl and heteroaryl ring systems are selected from the group ofacceptable substituents described below.

For brevity, the term “aryl” when used in combination with other terms(e.g., aryloxy, arylthioxy, arylalkyl) optionally includes both aryl andheteroaryl rings as defined above. Thus, the term “arylalkyl” optionallyincludes those radicals in which an aryl group is attached to an alkylgroup (e.g., benzyl, phenethyl, pyridylmethyl and the like) includingthose alkyl groups in which a carbon atom (e.g., a methylene group) hasbeen replaced by, for example, an oxygen atom (e.g., phenoxymethyl,2-pyridyloxymethyl, 3-(1-naphthyloxy)propyl, and the like).

Each of the above terms (e.g., “alkyl,” “heteroalkyl,” “aryl” and“heteroaryl”) optionally include both substituted and unsubstitutedforms of the indicated radical. Preferred substituents for each type ofradical are provided below.

Substituents for the alkyl and heteroalkyl radicals (including thosegroups often referred to as alkylene, alkenyl, heteroalkylene,heteroalkenyl, alkynyl, cycloalkyl, heterocycloalkyl, cycloalkenyl, andheterocycloalkenyl) are generically referred to as “alkyl groupsubstituents,” and they can be one or more of a variety of groupsselected from, but not limited to: substituted or unsubstituted aryl,substituted or unsubstituted heteroaryl, substituted or unsubstitutedheterocycloalkyl, —OR′, ═O, ═NR′, ═N—OR′, —NR′R″, —SR′, -halogen,—SiR′R″R′″, —OC(O)R′, —C(O)R′, —CO₂R′, —CONR′R″, —OC(O)NR′R″,—NR″C(O)R′, —NR′—C(O)NR″R′″, —NR″C(O)₂R′, —NR—C(NR′R″R′″)═NR″″,—NR—C(NR′R″)═NR′″, —S(O)R′, —S(O)₂R′, —S(O)₂NR′R″, —NRSO₂R′, —CN and—NO₂ in a number ranging from zero to (2m′+1), where m′ is the totalnumber of carbon atoms in such radical. R′, R″, R′″ and R″″ eachpreferably independently refer to hydrogen, substituted or unsubstitutedheteroalkyl, substituted or unsubstituted aryl, e.g., aryl substitutedwith 1-3 halogens, substituted or unsubstituted alkyl, alkoxy orthioalkoxy groups, or arylalkyl groups. When a compound of the inventionincludes more than one R group, for example, each of the R groups isindependently selected as are each R′, R″, R′″ and R″″ groups when morethan one of these groups is present. When R′ and R″ are attached to thesame nitrogen atom, they can be combined with the nitrogen atom to forma 5-, 6-, or 7-membered ring. For example, —NR′R″ is meant to include,but not be limited to, 1-pyrrolidinyl and 4-morpholinyl. From the abovediscussion of substituents, one of skill in the art will understand thatthe term “alkyl” is meant to include groups including carbon atoms boundto groups other than hydrogen groups, such as haloalkyl (e.g., —CF₃ and—CH₂CF₃) and acyl (e.g., —C(O)CH₃, —C(O)CF₃, —C(O)CH₂OCH₃, and thelike).

Similar to the substituents described for the alkyl radical,substituents for the aryl and heteroaryl groups are generically referredto as “aryl group substituents.” The substituents are selected from, forexample: substituted or unsubstituted alkyl, substituted orunsubstituted aryl, substituted or unsubstituted heteroaryl, substitutedor unsubstituted heterocycloalkyl, —OR′, ═O, ═NR′, ═N—OR′, —NR′R″, —SR′,-halogen, —SiR′R″R′″, —OC(O)R′, —C(O)R′, —CO₂R′, —CONR′R″, —OC(O)NR′R″,—NR″C(O)R′, —NR′—C(O)NR″R′″, —NR″C(O)₂R′, —NR—C(NR′R″R′″)═NR″″,—NR—C(NR′R″)═NR′″, —S(O)R′, —S(O)₂R′, —S(O)₂NR′R″, —NRSO₂R′, —CN and—NO₂, —R′, —N₃, —CH(Ph)₂, fluoro(C₁-C₄)alkoxy, and fluoro(C₁-C₄)alkyl,in a number ranging from zero to the total number of open valences onthe aromatic ring system; and where R′, R″, R′″ and R″″ are preferablyindependently selected from hydrogen, substituted or unsubstitutedalkyl, substituted or unsubstituted heteroalkyl, substituted orunsubstituted aryl and substituted or unsubstituted heteroaryl. When acompound of the invention includes more than one R group, for example,each of the R groups is independently selected as are each R′, R″, R′″and R″″ groups when more than one of these groups is present.

Two of the substituents on adjacent atoms of the aryl or heteroaryl ringmay optionally be replaced with a substituent of the formula-T-C(O)—(CRR′)_(q)—U—, wherein T and U are independently —NR—, —O—,—CRR′— or a single bond, and q is an integer of from 0 to 3.Alternatively, two of the substituents on adjacent atoms of the aryl orheteroaryl ring may optionally be replaced with a substituent of theformula -A-(CH₂)_(r)—B—, wherein A and B are independently —CRR′—, —O—,—NR—, —S—, —S(O)—, —S(O)₂—, —S(O)₂NR′— or a single bond, and r is aninteger of from 1 to 4. One of the single bonds of the new ring soformed may optionally be replaced with a double bond. Alternatively, twoof the substituents on adjacent atoms of the aryl or heteroaryl ring mayoptionally be replaced with a substituent of the formula—(CRR′)_(s)—X—(CR″R′″)_(d)—, where s and d are independently integers offrom 0 to 3, and X is —O—, —NR′—, —S—, —S(O)—, —S(O)₂—, or —S(O)₂NR′—.The substituents R, R′, R″ and R′″ are preferably independently selectedfrom hydrogen or substituted or unsubstituted (C₁-C₆)alkyl.

As used herein, the term “acyl” describes a substituent containing acarbonyl residue, C(O)R. Exemplary species for R include H, halogen,substituted or unsubstituted alkyl, substituted or unsubstituted aryl,substituted or unsubstituted heteroaryl, and substituted orunsubstituted heterocycloalkyl.

As used herein, the term “fused ring system” means at least two rings,wherein each ring has at least 2 atoms in common with another ring.“Fused ring systems may include aromatic as well as non aromatic rings.Examples of “fused ring systems” are naphthalenes, indoles, quinolines,chromenes and the like.

As used herein, the term “heteroatom” includes oxygen (O), nitrogen (N),sulfur (S) and silicon (Si), boron (B) and phosphorus (P).

The symbol “R” is a general abbreviation that represents a substituentgroup, e.g., one that is selected from substituted or unsubstitutedalkyl, substituted or unsubstituted heteroalkyl, substituted orunsubstituted aryl, substituted or unsubstituted heteroaryl, andsubstituted or unsubstituted heterocycloalkyl groups.

The term “pharmaceutically acceptable salts” includes salts of theactive compounds which are prepared with relatively nontoxic acids orbases, depending on the particular substituents found on the compoundsdescribed herein. When compounds of the present invention containrelatively acidic functionalities, base addition salts can be obtainedby contacting the neutral form of such compounds with a sufficientamount of the desired base, either neat or in a suitable inert solvent.Examples of pharmaceutically acceptable base addition salts includesodium, potassium, calcium, ammonium, organic amino, or magnesium salt,or a similar salt. When compounds of the present invention containrelatively basic functionalities, acid addition salts can be obtained bycontacting the neutral form of such compounds with a sufficient amountof the desired acid, either neat or in a suitable inert solvent.Examples of pharmaceutically acceptable acid addition salts includethose derived from inorganic acids like hydrochloric, hydrobromic,nitric, carbonic, monohydrogencarbonic, phosphoric,monohydrogenphosphoric, dihydrogenphosphoric, sulfuric,monohydrogensulfuric, hydriodic, or phosphorous acids and the like, aswell as the salts derived from relatively nontoxic organic acids likeacetic, propionic, isobutyric, maleic, malonic, benzoic, succinic,suberic, fumaric, lactic, mandelic, phthalic, benzenesulfonic,p-tolylsulfonic, citric, tartaric, methanesulfonic, and the like. Alsoincluded are salts of amino acids such as arginate and the like, andsalts of organic acids like glucuronic or galactunoric acids and thelike (see, for example, Berge et al., Journal of Pharmaceutical Science,66: 1-19 (1977)). Certain specific compounds of the present inventioncontain both basic and acidic functionalities that allow the compoundsto be converted into either base or acid addition salts.

The neutral forms of the compounds are preferably regenerated bycontacting the salt with a base or acid and isolating the parentcompound in the conventional manner. The parent form of the compounddiffers from the various salt forms in certain physical properties, suchas solubility in polar solvents, but otherwise the salts are equivalentto the parent form of the compound for the purposes of the presentinvention.

In addition to salt forms, the present invention provides compounds,which are in a prodrug form. Prodrugs of the compounds described hereinare those compounds that readily undergo chemical changes underphysiological conditions to provide the compounds of the presentinvention. Additionally, prodrugs can be converted to the compounds ofthe present invention by chemical or biochemical methods in an ex vivoenvironment. For example, prodrugs can be slowly converted to thecompounds of the present invention when placed in a transdermal patchreservoir with a suitable enzyme or chemical reagent.

Certain compounds of the present invention can exist in unsolvated formsas well as solvated forms, including hydrated forms. In general, thesolvated forms are equivalent to unsolvated forms and are encompassedwithin the scope of the present invention. Certain compounds of thepresent invention may exist in multiple crystalline or amorphous forms.In general, all physical forms are equivalent for the uses contemplatedby the present invention and are intended to be within the scope of thepresent invention.

Certain compounds of the present invention possess asymmetric carbonatoms (optical centers) or double bonds; the racemates, diastereomers,geometric isomers and individual isomers are encompassed within thescope of the present invention.

The compounds of the invention may be prepared as a single isomer (e.g.,enantiomer, cis-trans, positional, diastereomer) or as a mixture ofisomers. In a preferred embodiment, the compounds are prepared assubstantially a single isomer. Methods of preparing substantiallyisomerically pure compounds are known in the art. For example,enantiomerically enriched mixtures and pure enantiomeric compounds canbe prepared by using synthetic intermediates that are enantiomericallypure in combination with reactions that either leave the stereochemistryat a chiral center unchanged or result in its complete inversion.Alternatively, the final product or intermediates along the syntheticroute can be resolved into a single stereoisomer. Techniques forinverting or leaving unchanged a particular stereocenter, and those forresolving mixtures of stereoisomers are well known in the art and it iswell within the ability of one of skill in the art to choose andappropriate method for a particular situation. See, generally, Furnisset al. (eds.), VOGEL'S ENCYCLOPEDIA OF PRACTICAL ORGANIC CHEMISTRY5^(TH) ED., Longman Scientific and Technical Ltd., Essex, 1991, pp.809-816; and Heller, Acc. Chem. Res. 23: 128 (1990).

The graphic representations of racemic, ambiscalemic and scalemic orenantiomerically pure compounds used herein are taken from Maehr, J.Chem. Ed., 62: 114-120 (1985): solid and broken wedges are used todenote the absolute configuration of a chiral element; wavy linesindicate disavowal of any stereochemical implication which the bond itrepresents could generate; solid and broken bold lines are geometricdescriptors indicating the relative configuration shown but not implyingany absolute stereochemistry; and wedge outlines and dotted or brokenlines denote enantiomerically pure compounds of indeterminate absoluteconfiguration.

The terms “enantiomeric excess” and diastereomeric excess” are usedinterchangeably herein. Compounds with a single stereocenter arereferred to as being present in “enantiomeric excess,” those with atleast two stereocenters are referred to as being present in“diastereomeric excess.”

The compounds of the present invention may also contain unnaturalproportions of atomic isotopes at one or more of the atoms thatconstitute such compounds. For example, the compounds may beradiolabeled with radioactive isotopes, such as for example tritium(³H), iodine-125 (¹²⁵I) or carbon-14 (¹⁴C). All isotopic variations ofthe compounds of the present invention, whether radioactive or not, areintended to be encompassed within the scope of the present invention.

“Reactive functional group,” as used herein refers to groups including,but not limited to, olefins, acetylenes, alcohols, phenols, ethers,oxides, halides, aldehydes, ketones, carboxylic acids, esters, amides,cyanates, isocyanates, thiocyanates, isothiocyanates, amines,hydrazines, hydrazones, hydrazides, diazo, diazonium, nitro, nitriles,mercaptans, sulfides, disulfides, sulfoxides, sulfones, sulfonic acids,sulfinic acids, acetals, ketals, anhydrides, sulfates, sulfenic acidsisonitriles, amidines, imides, imidates, nitrones, hydroxylamines,oximes, hydroxamic acids thiohydroxamic acids, allenes, ortho esters,sulfites, enamines, ynamines, ureas, pseudoureas, semicarbazides,carbodiimides, carbamates, imines, azides, azo compounds, azoxycompounds, and nitroso compounds. Reactive functional groups alsoinclude those used to prepare bioconjugates, e.g., N-hydroxysuccinimideesters, maleimides and the like. Methods to prepare each of thesefunctional groups are well known in the art and their application ormodification for a particular purpose is within the ability of one ofskill in the art (see, for example, Sandler and Karo, eds. ORGANICFUNCTIONAL GROUP PREPARATIONS, Academic Press, San Diego, 1989).

“Non-covalent protein binding groups” are moieties that interact with anintact or denatured polypeptide in an associative manner. Theinteraction may be either reversible or irreversible in a biologicalmilieu. The incorporation of a “non-covalent protein binding group” intoa chelating agent or complex of the invention provides the agent orcomplex with the ability to interact with a polypeptide in anon-covalent manner. Exemplary non-covalent interactions includehydrophobic-hydrophobic and electrostatic interactions. Exemplary“non-covalent protein binding groups” include anionic groups, e.g.,phosphate, thiophosphate, phosphonate, carboxylate, boronate, sulfate,sulfone, sulfonate, thiosulfate, and thiosulfonate.

As used herein, “linking member” or “linking moiety” refers to acovalent chemical bond that preferentially includes at least oneheteroatom. Exemplary linking moieties include —C(O)NH—, —C(O)O—, —NH—,—S—, —O—, and the like.

The term “targeting moiety” is intended to mean any moiety attached tothe complexes of the invention. The targeting moiety can be a smallmolecule, which is intended to include both non-peptides and peptides.The targeting group can also be a macromolecule, which includessaccharides, lectins, receptors, ligands for receptors, proteins such asBSA, antibodies, solid supports and so forth. The targeting group canalso be a polymer, such as a plastic surface, a poly-ethyleneglycolderivative and the like.

The symbol

, whether utilized as a bond or displayed perpendicular to a bondindicates the point at which the displayed moiety is attached to theremainder of the molecule, solid support, etc.

3. Compositions

Chelating Agents and Complexes

In one embodiment, the invention provides organic ligand contains atleast one 1-hydroxy-2-pyridinone (1,2-HOPO) subunit as a chelatingmoiety. The HOPO subunit is optionally covalently linked to a scaffoldmoiety. In an exemplary embodiment, the chelate complexes a lanthanideion and forms a luminescent lanthanide complex of the invention.Alternatively, the metal ion is an actinide or other metal ion (e.g.,transition metal ion).

Throughout this specification, the chelating subunits are exemplified asbeing complexed with a metal ion having a +3 charge. The chemicalformulae showing this representation are intended to also encompass theunmetallated chelating agents as well as complexes in which the metalion has a charge other than +3, e.g., U⁶⁺ or Pu⁴⁺.

The chelates and complexes of the invention can contain any number of“free chelating moieties” and “linked chelating moieties”, wherein a“linked chelating moiety” is covalently linked to at least one otherchelating moiety through a scaffold moiety and wherein a “free chelatingmoiety” is not covalently linked to another chelating moiety through ascaffold moiety.

In one exemplary embodiment, the complex of the invention is formedbetween a metal ion (e.g, a lanthanide ion or actinide ion) and oneorganic ligand having four or more chelating moieties that are linkedthrough a scaffold moiety. In another exemplary embodiment, the complexis formed between a lanthanide ion and two organic ligands, wherein eachorganic ligand is composed of two chelating moieties that are covalentlylinked through a scaffold moiety. In yet another exemplary embodiment,the complex is formed utilizing an organic ligand containing twochelating moieties that are linked through a scaffold moiety as well astwo “free chelating moieties”. Other permutations of “linked-” and “freechelating moieties” are encompassed within the scope of the presentinvention.

In addition, the complexes between the metal ion and the organic ligandsmay be charged or uncharged. For instance, in those complexes whereinthe overall electric charge is negative, the negative charge may be“offset” by a cation, such as a quaternary amine (e.g., NMe₄ ⁺).

Preferred complexes of the invention include those in which the organicligand complexes the metal ion through oxygen atoms. Even more preferredis a chelate that complexes metal ions only through oxygen atoms. Afurther preferred complex includes an organic ligand that has 8 donoroxygen atoms that are coordinated to the metal ion, e.g., lanthanideion.

Currently preferred metal ions include, but are not limited to Fe³⁺,Gd³⁺, Eu³⁺, Tb³⁺. Am³⁺, Pu⁴⁺, Np⁴⁺, Np⁵⁺ and U⁶⁺ ions.

In one embodiment, the present invention provides a metal complex, e.g.,a luminescent complex between a metal ion, e.g., a lanthanide ion oractinide ion, and an organic ligand that includes a chelating moiety ofFormula (I):

In Formula (I), R¹, R², R³ and R⁴ are members independently selectedfrom H, an aryl group substituent as defined herein and a linker to ascaffold or functional moiety. M⁺³ is metal ion, e.g., a lanthanide ionforming the complex, e.g., the luminescent complex, with the organicligand.

The complexes of the invention can contain one or more chelatingmoieties, each optionally based on 1-hydroxy-2-pyridinone (1,2-HOPO)subunits of Formula (I).

In one exemplary embodiment, in Formula (I), R¹, R², R³, and R⁴ aremembers independently selected from H, substituted or unsubstitutedalkyl, substituted or unsubstituted heteroalkyl, substituted orunsubstituted aryl, substituted or unsubstituted heteroaryl, substitutedor unsubstituted heterocycloalkyl, halogen, CN, CF₃, —C(O)R¹⁷,—SO₂NR¹⁷R¹⁸, —NR¹⁷R¹⁸, —OR¹⁷, —S(O)₂R¹⁷, —COOR¹⁷, —S(O)₂OR¹⁷, —OC(O)R¹⁷,—C(O)NR¹⁷R¹⁸, —NR¹⁷C(O)R¹⁸, —NR¹⁷SO₂R¹⁸, —NO₂, a linker to a functionalmoiety and a linker to a scaffold moiety. At least two of R¹, R², R³ andR⁴ are optionally joined to form a ring system which is a memberselected from substituted or unsubstituted cycloalkyl, substituted orunsubstituted heterocycloalkyl, substituted or unsubstituted aryl andsubstituted or unsubstituted heteroaryl. R¹⁷ and R¹⁸ are each membersindependently selected from H, substituted or unsubstituted alkyl,substituted or unsubstituted heteroalkyl, substituted or unsubstitutedaryl, substituted or unsubstituted heteroaryl and substituted orunsubstituted heterocycloalkyl, a linker to a functional moiety and alinker to a scaffold moiety. R¹⁷ and R¹⁸, together with the atoms towhich they are attached, are optionally joined to form a 5- to7-membered ring.

Exemplary linker moieties include a bond (“zero-order”), —C(O)NR⁵—,—C(O)O—, —C(O)S—, and —C(O)CR²⁰R²¹, wherein R⁵, R²⁰ and R²¹ are membersindependently selected from H, substituted or unsubstituted alkyl,substituted or unsubstituted heteroalkyl, substituted or unsubstitutedaryl, substituted or unsubstituted heteroaryl and substituted orunsubstituted heterocycloalkyl. Preferred linkers include C₁-C₁₀,preferably, C₁-C₆ substituted or unsubstituted alkyl or substituted orunsubstituted heteroalkyl moieties.

In one exemplary embodiment, the organic ligand is an amide derived from1-hydroxy-2-pyridinone-6-carboxylic acid. Exemplary amides include thosein which R¹ is —C(O)NR¹⁷R¹⁸. In another exemplary embodiment, R¹⁷ is Hand R¹⁸ is substituted or unsubstituted alkyl. Two exemplary amides areshown below. Both the hexylamide and the decylamide showed strongluminescence under long-wave UV light when mixed with an aqueoussolution of a lanthanide ion.

In another exemplary embodiment, the 1,2-HOPO subunit is covalentlylinked to a scaffold moiety and the chelating moiety of Formula (I) hasthe structure:

wherein X is a scaffold moiety, and Y is a linker moiety. Exemplarylinker moieties include a bond (“zero-order”), —C(O)NR⁵—, —C(O)O—,—C(O)S—, and −C(O)CR²⁰R²¹, wherein R⁵, R²⁰ and R²¹ are membersindependently selected from H, substituted or unsubstituted alkyl,substituted or unsubstituted heteroalkyl, substituted or unsubstitutedaryl, substituted or unsubstituted heteroaryl and substituted orunsubstituted heterocycloalkyl.

In yet another embodiment, the hydroxypyridinone subunit of the complexhas the structure:

wherein X and R⁵ are as defined above. The heterocycle or the aryl ringare optionally functionalized with one or more substituent definedherein as an “aryl group substituent” or an “alkyl group substituent.”

In a further embodiment, the chelating agents and their complexes, e.g.,luminescent complexes, of the invention contain one or more chelatingmoieties that, in addition to a 1,2-HOPO moiety, include a structuredistinct from the 1,2-HOPO derivatives discussed above. In a preferredembodiment, each of those chelating moieties is independently selectedfrom a structure according to Formula (II):

In Formula (II), the chelating agent is shown in the form of itscomplex. It will be apparent to those of skill in the art that Formula(II) also discloses the uncomplexed chelating agent. In one exemplaryembodiment, in Formula (II), each R⁶, R⁷, R⁸, and R⁹ in each chelatingmoiety are members independently selected from H, substituted orunsubstituted alkyl, substituted or unsubstituted heteroalkyl,substituted or unsubstituted aryl, substituted or unsubstitutedheteroaryl, substituted or unsubstituted heterocycloalkyl, halogen, CN,CF₃, —C(O)R¹⁷, —SO₂NR¹⁷R¹⁸, —NR¹⁷R¹⁸, —OR¹⁷, —S(O)₂R¹⁷, —COOR¹⁷,—S(O)₂OR¹⁷, —OC(O)R¹⁷, —C(O)NR¹⁷R¹⁸, —NR¹⁷C(O)R¹⁸, —NR¹⁷SO₂R¹⁸, —NO₂, alinker to a functional moiety, and a linker to a scaffold moiety. Atleast two of R⁶, R⁷, R⁸ and R⁹ are optionally joined to form a ringsystem which is a member selected from substituted or unsubstitutedcycloalkyl, substituted or unsubstituted heterocycloalkyl, substitutedor unsubstituted aryl and substituted or unsubstituted heteroaryl. R¹⁷and R¹⁸ are each members independently selected from H, substituted orunsubstituted alkyl, substituted or unsubstituted heteroalkyl,substituted or unsubstituted aryl, substituted or unsubstitutedheteroaryl and substituted or unsubstituted heterocycloalkyl, a linkerto a functional moiety and a linker to a scaffold moiety. R¹⁷ and R¹⁸,together with the atoms to which they are attached, are optionallyjoined to form a 5- to 7-membered ring.

A and B in Formula (II) are members independently selected from carbon,nitrogen, sulfur and oxygen. D is a member selected from carbon andnitrogen. If A is oxygen or sulfur, R⁹ is preferably not present; and ifB is oxygen or sulfur, R⁷ is preferably not present.

The chelating moiety of Formula (II) is preferably not3-hydroxy-2-pyridinone:

or this moiety complexed with a metal ion.

In one exemplary embodiment, the chelating moieties of Formula (II) aremembers independently selected from the following structures.

Similar to Formula (II), these structures should be interpreted asdisclosing both the complexed and uncomplexed chelating agents. Inanother exemplary embodiment, R⁶ in Formula (II) represents a linker toa scaffold moiety. Exemplary chelating moieties according to this aspecthave the following structures:

wherein X is a scaffold moiety. R⁵ and R¹⁰ are members independentlyselected from H, substituted or unsubstituted alkyl, substituted orunsubstituted heteroalkyl, substituted or unsubstituted aryl,substituted or unsubstituted heteroaryl, substituted or unsubstitutedheterocycloalkyl. R¹¹ is a member selected from H, substituted orunsubstituted alkyl, substituted or unsubstituted heteroalkyl,substituted or unsubstituted aryl, substituted or unsubstitutedheteroaryl, substituted or unsubstituted heterocycloalkyl, and afunctional moiety. R^(9′) in the pyrimidinone is a member selected fromsubstituted or unsubstituted alkyl, substituted or unsubstitutedheteroalkyl, substituted or unsubstituted aryl, substituted orunsubstituted heteroaryl, and substituted or unsubstitutedheterocycloalkyl and is preferably a member selected from C₁-C₆ alkyl.

In one embodiment, two or more of the chelating moieties, which areindependently selected from Formula (I) and Formula (II) can becovalently linked through a scaffold moiety. This is, for example, thecase when at least one of R¹, R², R³ and R⁴ in Formula (I) is covalentlylinked to a scaffold moiety, wherein the scaffold moiety is covalentlylinked to at least one chelating moiety of Formula (II).

Thus, in an exemplary embodiment the luminescent complexes of theinvention have a structure according to Formula (III):

In Formula (III) Z is a member selected from substituted orunsubstituted alkyl, substituted or unsubstituted heteroalkyl,substituted or unsubstituted aryl, substituted or unsubstitutedheteroaryl, substituted or unsubstituted heterocycloalkyl, N, NR³⁰, Oand S. In an exemplary embodiment, Z is CR³¹R³². R³⁰, R³¹ and R³² aremembers independently selected from H, substituted or unsubstitutedalkyl, substituted or unsubstituted heteroalkyl, substituted orunsubstituted aryl, substituted or unsubstituted heteroaryl, substitutedor unsubstituted heterocycloalkyl and a linker to a functional moiety.In another exemplary embodiment, Z is substituted with a chelatingmoiety. The integer p is selected from 1-3 and q is an integer selectedfrom 0-2. The sum of p and q is preferably not greater than 4, and if Zis O or S, the sum of p and q is preferably 2. Y¹ and Y² are linkermoieties. In one exemplary embodiment, each of Y¹ and Y² is a memberindependently selected from —C(O)NR⁵—, —C(O)O—, —C(O)S—, and—C(O)CR²⁰R²¹, wherein R⁵, R²⁰ and R²¹ are members independently selectedfrom H, substituted or unsubstituted alkyl, substituted or unsubstitutedheteroalkyl, substituted or unsubstituted aryl, substituted orunsubstituted heteroaryl, substituted or unsubstituted heterocycloalkyland a functional moiety.

L¹ and L² are linker groups, and each L¹ and L² is a memberindependently selected from a bond, substituted or unsubstituted alkyl,substituted or unsubstituted heteroalkyl, substituted or unsubstitutedaryl, substituted or unsubstituted heteroaryl and substituted orunsubstituted heterocycloalkyl. At least one of Z, Y¹, Y², L¹ and L² isoptionally substituted with a functional moiety. In an exemplaryembodiment, Z is O and L¹ and L² are each ethyl.

In one exemplary embodiment, Z is NR³⁰ (e.g., when the sum of p and q is2), wherein R³⁰ is a member selected from substituted or unsubstitutedalkyl, substituted or unsubstituted heteroalkyl, substituted orunsubstituted aryl, substituted or unsubstituted heteroaryl, substitutedor unsubstituted heterocycloalkyl and a linker to a functional moiety.

Tetradentate Ligands

In one embodiment, the organic ligand is a tetradentate ligand.Exemplary tetradentate ligands include:

Hexadentate Ligands

In another exemplary embodiment, the organic ligand is a hexadentateligand. Exemplary hexadentate ligands include rigid and flexiblestructures:

Octadentate Ligands

In another embodiment, the luminescent complex of the invention includesan octadentate ligand having a structure according to Formula (IV):

wherein Z, L¹, L², Y¹, Y², R², R³, R⁴, R⁷, R⁸, R⁹, A, B and D are asdefined above for Formula (I), Formula (II) and Formula (III). InFormula (IV) at least one of Z, Y¹, Y², L¹ and L² is substituted with amoiety having the structure:

L³ is a linker group, which is a member selected from a bond,substituted or unsubstituted alkyl, substituted or unsubstitutedheteroalkyl, substituted or unsubstituted aryl, substituted orunsubstituted heteroaryl and substituted or unsubstitutedheterocycloalkyl. In an exemplary embodiment L³ is substituted with oneor more groups that include a chelating moiety. In another embodiment,L³ is chosen to increase the water solubility of the complex.Accordingly, in one example, L³ includes an ether group or a polyethermoiety. In a preferred embodiment, L³ includes 2 to 10 linear atoms, andmore preferably 2 to 8 linear atoms. Q has the structure of Formula (V):

wherein Z² is a member selected from substituted or unsubstituted alkyl,substituted or unsubstituted heteroalkyl, substituted or unsubstitutedaryl, substituted or unsubstituted heteroaryl, substituted orunsubstituted heterocycloalkyl, N, NR³⁰, O and S. In an exemplaryembodiment, Z² is CR³¹R³². R³⁰, R³¹ and R³² are as defined above. Inanother exemplary embodiment, Z² is substituted with a chelating moiety.Y³ and Y⁴ are linker moieties, which are members independently selectedfrom —C(O), —C(O)NR⁵—, —C(O)O—, —C(O)S—, and —C(O)CR²⁰R²¹, wherein R⁵,R²⁰ and R²¹ are as defined above. L⁴ and L⁵ are linker groups, which aremembers independently selected from a bond, substituted or unsubstitutedalkyl, substituted or unsubstituted heteroalkyl, substituted orunsubstituted aryl, substituted or unsubstituted heteroaryl andsubstituted or unsubstituted heterocycloalkyl. In Formula (V), at leastone of Z², Y³, Y⁴, L⁴ and L⁵ is linked to L³. At least one of thechelating moieties of Formula (V) is preferably a 1,2-HOPO unit.

Exemplary octadentate ligands include those with linear as well astetrapodal topology:

Other examples for ligands with tetrapodal topology include:

L³ can be positioned to link two sub-structures of a ligand in thecenter or “off-center”, for instance as shown below:

In an exemplary embodiment, the organic ligands of the invention canhave higher than octadentate denticities. Those can, for example, begenerated using scaffold moieties with more than four functional groups(e.g. NH₂ groups). In one example, additional chelating moieties are notused for chelation but instead may be used for protecting the centralmetal ion from water coordination.

Exemplary decadentate ligands include the following molecules, whichalso carry exemplary functional moieties:

Scaffold Moiety

The scaffold moiety of the invention can be any moiety useful forcovalently linking two or more chelating moieties. In one embodiment,the scaffold moiety is a member selected from substituted orunsubstituted alkyl and substituted or unsubstituted heteroalkyl.Exemplary scaffold moieties include linear or branched ethers andamines.

Other exemplary scaffolds include, but are not limited to:

A generally preferred moiety for at least one of the X radicals is the1,2-HOPO amide moiety shown above, however, those of skill in the artwill appreciate that other chelating agents including, withoutlimitation, a chelating moiety according to Formula (II) hereinabove. Ineach of the scaffold structures, and the 1,2-HOPO structure set forthabove, the aryl moiety or alkyl moiety can be substituted with one ormore “aryl group substituent” or “alkyl group substituent” as definedherein.

Other scaffold moieties that include functional moieties (or a linker toa functional moiety) include linkers prepared by the following exemplarymethods.

Other functionalize scaffolds include those in which the chiral carbonis placed on the central ethylene bridge of H22-amine. An exemplaryroute to such a scaffold initiates with 2,3-Diaminopropionic acid, asits carboxyl group is connected directly to the amine backbone to give avery rigid geometry, extended carboxyl chain is needed to provideflexibility for eventual protein conjugating. A synthetic scheme to thescaffold is shown in scheme 1.2.

Variations on this synthesis include the use of a nitrophenylalanine ora BOC-amino group, which are optionally converted to carboxyl groups.Synthetic routes to these scaffolds are shown in Schemes 1.3 and 1.4.

Functional Moiety

In one exemplary embodiment, the complexes of the invention arederivatized with at least one functional moiety. The term “functionalmoiety” includes any substituent group, which is useful to link acomplex of the invention to another molecule. Such linkage can be eithercovalent or non-covalent. Hence, the functional moiety may contain areactive functional group. “Functional moiety” also includes anysubstituent group that includes a targeting moiety, such as apolypeptide, a ligand to a receptor, an antibody and the like.

The functional moiety is preferably attached, so that the resultingfunctionalized ligand will be able to undergo formation of stable metalion complexes. In one exemplary embodiment, the functional moiety can beattached to the scaffold moiety, for instance, to one of the linkergroups, such as L¹ or L² in Formula (III). In another exemplaryembodiment, the functional moiety is attached to one of the chelatingmoieties of Formula (I) or Formula (II). For example, the functionalmoiety can be part of R¹¹ in a TAM moiety. The functional moiety canalso be attached to any other linker moiety (e.g., R⁵ may include afunctional moiety) or linker group within the complex. In anotherexample, a functional moiety is attached to at least one of L¹, L², L³,L⁴ or L⁵ in Formula (IV) and/or Formula (V).

Exemplary organic ligands including a functional moiety are shown below:

In an exemplary embodiment, the functional moiety has the structure:

wherein L⁶ is a linker moiety, which is a member selected fromsubstituted or unsubstituted alkyl, substituted or unsubstitutedheteroalkyl, substituted or unsubstituted aryl, substituted orunsubstituted heteroaryl and substituted or unsubstitutedheterocycloalkyl. X¹ is a member selected from a reactive functionalgroup and a targeting moiety.Reactive Functional Groups

In one embodiment, the functional moiety includes a reactive functionalgroup, which can be used to covalently attach the ligand to a targetingmoiety, such as a protein, a small molecule, a lipid, a carbohydrate andthe like. Alternatively, the reactive functional group can be used tolink the ligand to a nano-particle of any kind. Reactive groups andclasses of reactions useful in practicing the present invention aregenerally those that are well known in the art of bioconjugatechemistry. Currently favored classes of reactions available withreactive functional groups of the invention are those which proceedunder relatively mild conditions. These include, but are not limited tonucleophilic substitutions (e.g., reactions of amines and alcohols withacyl halides and activated esters), electrophilic substitutions (e.g.,enamine reactions) and additions to carbon-carbon and carbon-heteroatommultiple bonds (e.g., Michael reactions and Diels-Alder reactions).These and other useful reactions are discussed, for example, in: March,ADVANCED ORGANIC CHEMISTRY, 3rd Ed., John Wiley & Sons, New York, 1985;Hermanson, BIOCONJUGATE TECHNIQUES, Academic Press, San Diego, 1996; andFeeney et al., MODIFICATION OF PROTEINS; Advances in Chemistry Series,Vol. 198, American Chemical Society, Washington, D.C., 1982.

a) Amines and Amino-Reactive Groups

In one embodiment, the reactive functional group is a member selectedfrom amines, such as a primary or secondary amine, hydrazines,hydrazides, and sulfonylhydrazides. Amines can, for example, beacylated, alkylated or oxidized. Useful non-limiting examples ofamino-reactive groups include N-hydroxysuccinimide (NHS) esters,sulfur-NHS esters, imidoesters, isocyanates, isothiocyanates,acylhalides, arylazides, p-nitrophenyl esters, aldehydes, sulfonylchlorides, thiazolides and carboxyl groups.

NHS esters and sulfur-NHS esters react preferentially with the primary(including aromatic) amino groups of the reaction partner. The imidazolegroups of histidines are known to compete with primary amines forreaction, but the reaction products are unstable and readily hydrolyzed.The reaction involves the nucleophilic attack of an amine on the acidcarboxyl of an NHS ester to form an amide, releasing theN-hydroxysuccinimide.

Imidoesters are the most specific acylating reagents for reaction withthe amine groups of e.g., a protein. At a pH between 7 and 10,imidoesters react only with primary amines. Primary amines attackimidates nucleophilically to produce an intermediate that breaks down toamidine at high pH or to a new imidate at low pH. The new imidate canreact with another primary amine, thus crosslinking two amino groups, acase of a putatively monofunctional imidate reacting bifunctionally. Theprincipal product of reaction with primary amines is an amidine that isa stronger base than the original amine. The positive charge of theoriginal amino group is therefore retained. As a result, imidoesters donot affect the overall charge of the conjugate.

Isocyanates (and isothiocyanates) react with the primary amines of theconjugate components to form stable bonds. Their reactions withsulfhydryl, imidazole, and tyrosyl groups give relatively unstableproducts.

Acylazides are also used as amino-specific reagents in whichnucleophilic amines of the reaction partner attack acidic carboxylgroups under slightly alkaline conditions, e.g. pH 8.5.

Arylhalides such as 1,5-difluoro-2,4-dinitrobenzene react preferentiallywith the amino groups and tyrosine phenolic groups of the conjugatecomponents, but also with its sulfhydryl and imidazole groups.

p-Nitrophenyl esters of carboxylic acids are also useful amino-reactivegroups. Although the reagent specificity is not very high, α- andε-amino groups appear to react most rapidly.

Aldehydes react with primary amines of the conjugate components (e.g.,ε-amino group of lysine residues). Although unstable, Schiff bases areformed upon reaction of the protein amino groups with the aldehyde.Schiff bases, however, are stable, when conjugated to another doublebond. The resonant interaction of both double bonds prevents hydrolysisof the Schiff linkage. Furthermore, amines at high local concentrationscan attack the ethylenic double bond to form a stable Michael additionproduct. Alternatively, a stable bond may be formed by reductiveamination.

Aromatic sulfonyl chlorides react with a variety of sites of theconjugate components, but reaction with the amino groups is the mostimportant, resulting in a stable sulfonamide linkage.

Free carboxyl groups react with carbodiimides, soluble in both water andorganic solvents, forming pseudoureas that can then couple to availableamines yielding an amide linkage. Yamada et al., Biochemistry 1981, 20:4836-4842, e.g., teach how to modify a protein with carbodiimides.

b) Sulfhydryl and Sulfhydryl-Reactive Groups

In another embodiment, the reactive functional group is a memberselected from a sulfhydryl group (which can be converted to disulfides)and sulfhydryl-reactive groups. Useful non-limiting examples ofsulfhydryl-reactive groups include maleimides, alkyl halides, acylhalides (including bromoacetamide or chloroacetamide), pyridyldisulfides, and thiophthalimides.

Maleimides react preferentially with the sulfhydryl group of theconjugate components to form stable thioether bonds. They also react ata much slower rate with primary amino groups and the imidazole groups ofhistidines. However, at pH 7 the maleimide group can be considered asulfhydryl-specific group, since at this pH the reaction rate of simplethiols is 1000-fold greater than that of the corresponding amine.

Alkyl halides react with sulfhydryl groups, sulfides, imidazoles, andamino groups. At neutral to slightly alkaline pH, however, alkyl halidesreact primarily with sulfhydryl groups to form stable thioether bonds.At higher pH, reaction with amino groups is favored.

Pyridyl disulfides react with free sulfhydryl groups via disulfideexchange to give mixed disulfides. As a result, pyridyl disulfides arerelatively specific sulfhydryl-reactive groups.

Thiophthalimides react with free sulfhydryl groups to also formdisulfides.

c) Other Reactive Functional Groups

Other exemplary reactive functional groups include:

-   -   (i) carboxyl groups and various derivatives thereof including,        but not limited to, N-hydroxybenztriazole esters, acid halides,        acyl imidazoles, thioesters, p-nitrophenyl esters, alkyl,        alkenyl, alkynyl and aromatic esters;    -   (ii) hydroxyl groups, which can be converted to esters, ethers,        aldehydes, etc.;    -   (iii) haloalkyl groups, wherein the halide can be displaced with        a nucleophilic group such as, for example, an amine, a        carboxylate anion, thiol anion, carbanion, or an alkoxide ion,        thereby resulting in the covalent attachment of a new group at        the site of the halogen atom;    -   (iv) dienophile groups, which are capable of participating in        Diels-Alder reactions such as, for example, maleimido groups;    -   (v) aldehyde or ketone groups, such that subsequent        derivatization is possible via formation of carbonyl derivatives        such as, for example, imines, hydrazones, semicarbazones or        oximes, or via such mechanisms as Grignard addition or        alkyllithium addition;    -   (vi) alkenes, which can undergo, for example, cycloadditions,        acylation, Michael addition, etc;    -   (vii) epoxides, which can react with, for example, amines and        hydroxyl groups;    -   (ix) phosphoramidites and other standard functional groups        useful in nucleic acid synthesis and    -   (x) any other functional group useful to form a covalent bond        between the functionalized ligand and a molecular entity or a        surface.        d) Functional Groups with Non-Specific Reactivities

In addition to the use of site-specific reactive moieties, the presentinvention contemplates the use of non-specific reactive groups to linkthe ligand to a targeting moiety. Non-specific groups includephotoactivatable groups, for example.

Photoactivatable groups are ideally inert in the dark and are convertedto reactive species in the presence of light. In one embodiment,photoactivatable groups are selected from precursors of nitrenesgenerated upon heating or photolysis of azides. Electron-deficientnitrenes are extremely reactive and can react with a variety of chemicalbonds including N—H, O—H, C—H, and C═C. Although three types of azides(aryl, alkyl, and acyl derivatives) may be employed, arylazides arepresently preferred. The reactivity of arylazides upon photolysis isbetter with N—H and O—H than C—H bonds. Electron-deficient arylnitrenesrapidly ring-expand to form dehydroazepines, which tend to react withnucleophiles, rather than form C—H insertion products. The reactivity ofarylazides can be increased by the presence of electron-withdrawingsubstituents such as nitro or hydroxyl groups in the ring. Suchsubstituents push the absorption maximum of arylazides to longerwavelength. Unsubstituted arylazides have an absorption maximum in therange of 260-280 nm, while hydroxy and nitroarylazides absorbsignificant light beyond 305 nm. Therefore, hydroxy and nitroarylazidesare most preferable since they allow to employ less harmful photolysisconditions for the affinity component than unsubstituted arylazides.

In another preferred embodiment, photoactivatable groups are selectedfrom fluorinated arylazides. The photolysis products of fluorinatedarylazides are arylnitrenes, all of which undergo the characteristicreactions of this group, including C—H bond insertion, with highefficiency (Keana et al., J. Org. Chem. 55: 3640-3647, 1990).

In another embodiment, photoactivatable groups are selected frombenzophenone residues. Benzophenone reagents generally give highercrosslinking yields than arylazide reagents.

In another embodiment, photoactivatable groups are selected from diazocompounds, which form an electron-deficient carbene upon photolysis.These carbenes undergo a variety of reactions including insertion intoC—H bonds, addition to double bonds (including aromatic systems),hydrogen attraction and coordination to nucleophilic centers to givecarbon ions.

In still another embodiment, photoactivatable groups are selected fromdiazopyruvates. For example, the p-nitrophenyl ester of p-nitrophenyldiazopyruvate reacts with aliphatic amines to give diazopyruvic acidamides that undergo ultraviolet photolysis to form aldehydes. Thephotolyzed diazopyruvate-modified affinity component will react likeformaldehyde or glutaraldehyde forming intraprotein crosslinks.

It is well within the abilities of a person skilled in the art to selecta reactive functional group, according to the reaction partner. As anexample, an activated ester, such as an NHS ester will be useful tolabel a protein via lysine residues. Sulfhydryl reactive groups, such asmaleimides can be used to label proteins via amino acid residuescarrying an SH-group (e.g., cystein). Antibodies may be labeled by firstoxidizing their carbohydrate moieties (e.g., with periodate) andreacting resulting aldehyde groups with a hydrazine containing ligand.

The reactive functional groups can be chosen such that they do notparticipate in, or interfere with, the reactions necessary to assemblethe reactive ligand. Alternatively, a reactive functional group can beprotected from participating in the reaction by means of a protectinggroup. Those of skill in the art understand how to protect a particularfunctional group so that it does not interfere with a chosen set ofreaction conditions. For examples of useful protecting groups, see, forexample, Greene et al., PROTECTIVE GROUPS IN ORGANIC SYNTHESIS, JohnWiley & Sons, New York, 1991.

Targeting Moieties

Exemplary targeting moieties include small-molecule ligands, lipids,linear and cyclic peptides, polypeptides (e.g., EPO, insulin etc.),proteins, such as enzymes and receptors and fusion proteins. Othertargeting moieties include antibodies and antibody fragments (e.g.,those generated to recognize small-molecules and receptor ligands),antigens, nucleic acids (e.g. RNA and cDNA), carbohydrate moieties(e.g., polysaccharides), lipids and pharmacologically active molecules,such as toxins, pharmaceutical drugs and drugs of abuse (e.g. steroids).

Additional targeting moieties are selected from solid supports andpolymeric surfaces (e.g., polymeric beads and plastic sample reservoirs,such as plastic well-plates), sheets, fibers and membranes. Targetingmoieties also include particles (e.g., nano-particles) and drug-deliveryvehicles.

In one embodiment, the targeting moiety includes at least one unit of amacrocyclic compound. In another exemplary embodiment, the compound ofthe invention has a dendrimeric structure and encompasses severalligands of the invention covalently linked to each other. In a furtherexemplary embodiment, according to this aspect, a complex based on suchdendrimer includes at least two metal ions.

In another exemplary embodiment, the Linker moiety L⁶ or the targetingmoiety include a polyether, such as polyethylene glycol (PEG) andderivatives thereof. In one example, the polyether has a molecularweight between about 50 to about 10,000 daltons.

In one exemplary embodiment, the targeting moiety is a proteincontaining a lipid recognition motif. Exemplary lipid binding proteinsinclude those that bind to phosphatidylinositol, phosphatidylinositolphosphates or other biological lipids.

In another exemplary embodiment, the targeting moiety is substitutedwith a luminescence modifying group that allows luminescence energytransfer between a complex of the invention and the luminescencemodifying group when the complex is excited.

In one example, the functional moiety has the structure:

wherein L⁶ is a linker moiety, which is a member selected fromsubstituted or unsubstituted alkyl, substituted or unsubstitutedheteroalkyl, substituted or unsubstituted aryl, substituted orunsubstituted heteroaryl and substituted or unsubstitutedheterocycloalkyl. X¹ is a targeting moiety and Z⁴ is a luminescencemodifying group allowing luminescence energy transfer between saidcomplex and said luminescence modifying group when said complex isexcited.Linker Moiety L⁶

In one preferred embodiment, the linker moiety L⁶ of the functionalmoiety is long enough to avoid side reactions during synthesis (e.g.intra-molecular reactions, such as intra-molecular peptide bondformation), to allow coupling of the organic ligand or complex of theinvention to a targeting moiety and to allow the targeting moiety tofulfill its intended function. Useful linkers include those with about 2to about 50 linear atoms, preferably about 4 to about 20 linear atoms.

In one exemplary embodiment the linker moiety includes an aliphaticcarbon chain or a poly-ethyleneglycol (PEG) chain. Thus, the functionalmoiety includes a structure which is a member selected from:

Exemplary X² groups include OH, alkoxy, and one of the followingstructures:

wherein R²² is a member selected from H, substituted or unsubstitutedalkyl, substituted or unsubstituted heteroalkyl, substituted orunsubstituted aryl, substituted or unsubstituted heteroaryl andsubstituted or unsubstituted heterocycloalkyl. The integer v is selectedfrom 1 to 20, and w is an integer from 1 to 1,000.

In another exemplary embodiment, the functional moiety has thestructure:

wherein Z⁵ is a member selected from H, OR²³, SR²³, NHR²³, OCOR²⁴,OC(O)NHR²⁴, NHC(O)OR²³, OS(O)₂OR²³, and C(O)R²⁴. R²³ is a memberselected from H, substituted or unsubstituted alkyl, and substituted orunsubstituted heteroalkyl. R²⁴ is a member selected from H, OR²⁵,NR²⁵NH₂, SH, C(O)R²⁵, NR²⁵H, substituted or unsubstituted alkyl andsubstituted or unsubstituted heteroalkyl. R²⁵ is a member selected fromH, substituted or unsubstituted alkyl and substituted or unsubstitutedalkyl. X³ is a member selected from O, S and NR²⁶, wherein R²⁶ is amember selected from H, substituted or unsubstituted alkyl andsubstituted or unsubstituted heteroalkyl. The integers j an k aremembers independently selected from 1 to 20.

In linker arms with multiple reactive functional groups, a particularfunctional group can be chosen such that it does not participate in, orinterfere with, the reaction controlling the attachment of thefunctionalized spacer component to another ligand component.Alternatively, the reactive functional group can be protected fromparticipating in the reaction by the presence of a protecting group.Those of skill in the art understand how to protect a particularfunctional group from interfering with a chosen set of reactionconditions. For examples of useful protecting groups, See Greene et al.,PROTECTIVE GROUPS IN ORGANIC SYNTHESIS, John Wiley & Sons, New York,1991.

In one embodiment, the linker attaches the ligand to a targeting groupessentially irreversibly via a “stable bond” between the components. A“stable bond”, as used herein, is a bond, which maintains its chemicalintegrity over a wide range of conditions (e.g., amide, carbamate,carbon-carbon, ether, etc.). In another embodiment the linker attachestwo or more components by a “cleaveable bond”. A “cleaveable bond”, asused herein, is a bond which is designed to undergo scission underselected conditions. Cleaveable bonds include, but are not limited to,disulfide, imine, carbonate and ester bonds.

In an exemplary embodiment, the complex of the invention includes awater-soluble polymer as a scaffold moiety, or as a targeting moiety.Exemplary water-soluble polymers include polylysine, polyethylene glycol(PEG) or polydextran (Dresser, T. R. et al., J. Magn. Reson. Imaging1994, 4: 467)

Thus, in another embodiment, the invention provides a complex (e.g., ofFormula III), wherein at least one of R¹, R², R³, and R⁴ comprise amoiety derived from polyethylene glycol (PEG). PEG is used inbiotechnology and biomedical applications. The use of this agent hasbeen reviewed (POLY-ETHYLENE GLYCOL CHEMISTRY: BIOTECHNICAL ANDBIOMEDICAL APPLICATIONS, J. M. Harris, Ed., Plenum Press, New York,1992). Modification of enzymes (Chiu et al., J. Bioconjugate Chem., 4:290-295 (1993)), RGD peptides (Braatz et al., Bioconjugate Chem., 4:262-267 (1993)), liposomes (Zalipsky, S. Bioconjugate Chem., 4: 296-299(1993)), and CD4-IgG glycoprotein (Chamow et al., Bioconjugate Chem., 4:133-140 (1993)) are some of the recent advances in the use ofpolyethylene glycol. Surfaces treated with PEG have been shown to resistprotein deposition and have improved resistance to thrombogenicity whencoated on blood contacting biomaterials (Merrill, “Poly(ethylene oxide)and Blood Contact: A Chronicle of One Laboratory,” in POLY(ETHYLENEGLYCOL) CHEMISTRY: BIOTECHNICAL AND BIOMEDICAL APPLICATIONS, Harris,Ed., Plenum Press, New York, (1992), pp. 199-220).

Many routes are available for attaching a ligand or complex of theinvention onto a polymeric or oligomeric species. See, for example,Dunn, R. L., et al., Eds. POLYMERIC DRUGS AND DRUG DELIVERY SYSTEMS, ACSSymposium Series Vol. 469, American Chemical Society, Washington, D.C.1991; Herren et al., J. Colloid and Interfacial Science 115: 46-55(1987); Nashabeh et al., J. Chromatography 559: 367-383 (1991);Balachandar et al., Langmuir 6: 1621-1627 (1990); and Burns et al.,Biomaterials 19: 423-440 (1998).

Many activated derivatives of PEG are available commercially and in theliterature. It is well within the abilities of one of skill to choose,and synthesize if necessary, an appropriate activated PEG derivativewith which to prepare a substrate useful in the present invention. See,Abuchowski et al. Cancer Biochem. Biophys., 7: 175-186 (1984);Abuchowski et al., J. Biol. Chem., 252: 3582-3586 (1977); Jackson etal., Anal. Biochem., 165: 114-127 (1987); Koide et al., Biochem Biophys.Res. Commun., 111: 659-667 (1983)), tresylate (Nilsson et al., MethodsEnzymol., 104: 56-69 (1984); Delgado et al., Biotechnol. Appl. Biochem.,12: 119-128 (1990)); N-hydroxysuccinimide derived active esters(Buckmann et al., Makromol. Chem., 182: 1379-1384 (1981); Joppich etal., Makromol. Chem., 180: 1381-1384 (1979); Abuchowski et al., CancerBiochem. Biophys., 7: 175-186 (1984); Katre et al. Proc. Natl. Acad.Sci. U.S.A., 84: 1487-1491 (1987); Kitamura et al., Cancer Res., 51:4310-4315 (1991); Boccu et al., Z. Naturforsch., 38C: 94-99 (1983),carbonates (Zalipsky et al., POLY(ETHYLENE GLYCOL) CHEMISTRY:BIOTECHNICAL AND BIOMEDICAL APPLICATIONS, Harris, Ed., Plenum Press, NewYork, 1992, pp. 347-370; Zalipsky et al., Biotechnol. Appl. Biochem.,15: 100-114 (1992); Veronese et al., Appl. Biochem. Biotech., 11:141-152 (1985)), imidazolyl formates (Beauchamp et al., Anal. Biochem.,131: 25-33 (1983); Berger et al., Blood, 71: 1641-1647 (1988)),4-dithiopyridines (Woghiren et al., Bioconjugate Chem., 4: 314-318(1993)), isocyanates (Byun et al., ASAIO Journal, M649-M-653 (1992)) andepoxides (U.S. Pat. No. 4,806,595, issued to Noishiki et al., (1989).Other linking groups include the urethane linkage between amino groupsand activated PEG. See, Veronese, et al., Appl. Biochem. Biotechnol.,11: 141-152 (1985).

In another aspect, the present invention provides a metal complex as setforth above, which is attached to a dendrimer via a reactive functionalgroup. Similar to the linker group discussed above, the dendrimer willhave at least two reactive functional groups. In one embodiment, one ormore fully assembled ligand is attached to the dendrimer. Alternatively,the dendrimer is selected such that it serves as the linker and thechelate is formed directly on the dendrimer.

In one embodiment, complexes of the invention non-covalently bind tomacromolecules within a cell, tissue or body (Lauffer, R. B., Magn.Reson. Med. 1991, 22, 339). The binding causes an increasedconcentration and retention of the luminescent complex in the localizedregion of the biomolecule. The art is replete with examples of metalcomplexes designed to bind selected targets in vivo. For example, thecomplex MS-325 forms a noncovalent adduct with the blood protein humanserum albumin (HSA) (Parmalee, D. J. W. et al., Invest. Radiol. 1997,32, 741; Lauffer, R. B. P. et al., Radiology 1998, 207, 529). Lanthanidecomplexes have also been designed to target other macromolecules. Forexample, Gd-BOPTA was designed to target hepatocytes in order tofacilitate hepatobiliary imaging (Cavanga, F. M. et al., Invest. Radiol.1997, 32, 780).

Luminescence Modifying Groups (Donor and Acceptor Moieties)

The luminescent compounds of the invention can be used with a wide rangeof energy donor and acceptor molecules to construct luminescence energytransfer pairs, e.g., fluorescence energy transfer (FET) probes.Fluorophores useful in conjunction with the complexes of the inventionare known to those of skill in the art. See, for example, Cardullo etal., Proc. Natl. Acad. Sci. USA 85: 8790-8794 (1988); Dexter, D. L., J.of Chemical Physics 21: 836-850 (1953); Hochstrasser et al., BiophysicalChemistry 45: 133-141 (1992); Selvin, P., Methods in Enzymology 246:300-334 (1995); Steinberg, I. Ann. Rev. Biochem., 40: 83-114 (1971);Stryer, L. Ann. Rev. Biochem., 47: 819-846 (1978); Wang et al.,Tetrahedron Letters 31: 6493-6496 (1990); Wang et al., Anal. Chem. 67:1197-1203 (1995).

A non-limiting list of exemplary donor or acceptor moieties that can beused in conjunction with the luminescent complexes of the invention, isprovided in Table 1.

TABLE 1 Suitable Moieties Useful as Donors or Acceptors in FET Pairs4-acetamido-4′-isothiocyanatostilbene-2,2′disulfonic acid acridine andderivatives:     acridine     acridine isothiocyanate5-(2′-aminoethyl)aminonaphthalene-1-sulfonic acid (EDANS)4-amino-N-[3-vinylsulfonyl)phenyl]naphthalimide-3,5 disulfonateN-(4-anilino-1-naphthyl)maleimide anthranilamide BODIPY Brilliant Yellowcoumarin and derivatives: coumarin     7-amino-4-methylcoumarin (AMC,Coumarin 120)     7-amino-4-trifluoromethylcouluarin (Coumaran 151)cyanine dyes cyanosine 4′,6-diaminidino-2-phenylindole (DAPI)5′,5″-dibromopyrogallol-sulfonaphthalein (Bromopyrogallol Red)7-diethylamino-3-(4′-isothiocyanatophenyl)-4-methylcoumarindiethylenetriamine pentaacetate4,4′-diisothiocyanatodihydro-stilbene-2,2′-disulfonic acid4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid5-[dimethylamino]naphthalene-1-sulfonyl chloride (DNS, dansylchloride)4-(4′-dimethylaminophenylazo)benzoic acid (DABCYL)4-dimethylaminophenylazophenyl-4′-isothiocyanate (DABITC) eosin andderivatives:     eosin     eosin isothiocyanate erythrosin andderivatives:     erythrosin B     erythrosin isothiocyanate ethidiumfluorescein and derivatives:     5-carboxyfluorescein (FAM)    5-(4,6-dichlorotriazin-2-yl)aminofluorescein (DTAF)    2′,7′-dimethoxy-4′,5′-dichloro-6-carboxyfluorescein (JOE)    fluorescein     fluorescein isothiocyanate     QFITC (XRITC)fluorescamine IR144 IR1446 Malachite Green isothiocyanate4-methylumbelliferone ortho cresolphthalein nitrotyrosine pararosanilinePhenol Red B-phycoerythrin o-phthaldialdehyde pyrene and derivatives:    pyrene     pyrene butyrate     succinimidyl 1-pyrene butyratequantum dots Reactive Red 4 (Cibacron™ Brilliant Red 3B-A) rhodamine andderivatives:     6-carboxy-X-rhodamine (ROX)     6-carboxyrhodamine(R6G)     lissamine rhodamine B sulfonyl chloride rhodamine (Rhod)    rhodamine B     rhodamine 123 rhodamine X isothiocyanate    sulforhodamine B     sulforhodamine 101 sulfonyl chloride derivativeof sulforhodamine 101 (Texas Red)N,N,N′,N′-tetramethyl-6-carboxyrhodamine (TAMRA)     tetramethylrhodamine tetramethyl rhodamine isothiocyanate (TRITC) riboflavinrosolic acid lanthanide chelate derivatives

There is practical guidance available in the literature for selectingappropriate donor-acceptor pairs for particular probes, as exemplifiedby the following references: Pesce et al., Eds., FLUORESCENCESPECTROSCOPY (Marcel Dekker, New York, 1971); White et al., FLUORESCENCEANALYSIS: A PRACTICAL APPROACH (Marcel Dekker, New York, 1970). Theliterature also includes references providing exhaustive lists offluorescent and chromogenic molecules and their relevant opticalproperties, for choosing reporter-quencher pairs (see, for example,Berlman, HANDBOOK OF FLUORESCENCE SPECTRA OF AROMATIC MOLECULES, 2ndEdition (Academic Press, New York, 1971); Griffiths, COLOUR ANDCONSTITUTION OF ORGANIC MOLECULES (Academic Press, New York, 1976);Bishop, Ed., INDICATORS (Pergamon Press, Oxford, 1972); Haugland,HANDBOOK OF FLUORESCENT PROBES AND RESEARCH CHEMICALS (Molecular Probes,Eugene, 1992) Pringsheim, FLUORESCENCE AND PHOSPHORESCENCE (IntersciencePublishers, New York, 1949); and the like. Further, there is extensiveguidance in the literature for derivatizing reporter and quenchermolecules for covalent attachment via readily available reactive groupsthat can be added to a molecule.

The diversity and utility of chemistries available for conjugatingfluorophores to other molecules and surfaces is exemplified by theextensive body of literature on preparing nucleic acids derivatized withfluorophores. See, for example, Haugland (supra); Ullman et al., U.S.Pat. No. 3,996,345; Khanna et al., U.S. Pat. No. 4,351,760. Thus, it iswell within the abilities of those of skill in the art to choose anenergy exchange pair for a particular application and to conjugate themembers of this pair to a probe molecule, such as, for example, a smallmolecular bioactive material, nucleic acid, peptide or other polymer.

In a FET pair, it is generally preferred that an absorbance band of theacceptor substantially overlap a fluorescence emission band of thedonor. When the donor (fluorophore) is a component of a probe thatutilizes fluorescence resonance energy transfer (FRET), the donorfluorescent moiety and the quencher (acceptor) of the invention arepreferably selected so that the donor and acceptor moieties exhibitfluorescence resonance energy transfer when the donor moiety is excited.One factor to be considered in choosing the fluorophore-quencher pair isthe efficiency of fluorescence resonance energy transfer between them.Preferably, the efficiency of FRET between the donor and acceptormoieties is at least 10%, more preferably at least 50% and even morepreferably at least 80%. The efficiency of FRET can easily beempirically tested using the methods both described herein and known inthe art.

The efficiency of FRET between the donor-acceptor pair can also beadjusted by changing ability of the donor and acceptor to dimerize orclosely associate. If the donor and acceptor moieties are known ordetermined to closely associate, an increase or decrease in associationcan be promoted by adjusting the length of a linker moiety, or of theprobe itself, between the two fluorescent entities. The ability ofdonor-acceptor pair to associate can be increased or decreased by tuningthe hydrophobic or ionic interactions, or the steric repulsions in theprobe construct. Thus, intramolecular interactions responsible for theassociation of the donor-acceptor pair can be enhanced or attenuated.Thus, for example, the association between the donor-acceptor pair canbe increased by, for example, utilizing a donor bearing an overallnegative charge and an acceptor with an overall positive charge.

In addition to fluorophores that are attached directly to a probe, thefluorophores can also be attached by indirect means. In this embodiment,a ligand molecule (e.g., biotin) is preferably covalently bound to theprobe species. The ligand then binds to another molecules (e.g.,streptavidin) molecule, which is either inherently detectable orcovalently bound to a signal system, such as a fluorescent compound ofthe invention, or an enzyme that produces a fluorescent compound byconversion of a non-fluorescent compound. Useful enzymes of interest aslabels include, for example, hydrolases, particularly phosphatases,esterases and glycosidases, or oxidotases, particularly peroxidases.Fluorescent compounds include fluorescein and its derivatives, rhodamineand its derivatives, dansyl, umbelliferone, etc., as discussed above.For a review of various labeling or signal producing systems that can beused, see, U.S. Pat. No. 4,391,904.

Means of detecting fluorescent labels are well known to those of skillin the art. Thus, for example, fluorescent labels can be detected byexciting the fluorophore with the appropriate wavelength of light anddetecting the resulting fluorescence. The fluorescence can be detectedvisually, by means of photographic film, by the use of electronicdetectors such as charge coupled devices (CCDs) or photomultipliers andthe like. Similarly, enzymatic labels may be detected by providing theappropriate substrates for the enzyme and detecting the resultingreaction product.

IV. Methods

The complexes of the invention are useful as probes in a variety ofbiological assay systems and diagnostic applications. An overview ofassay systems, such as competitive assay formats, immunological assays,microarrays, membrane binding assays and enzyme activity assays, isgiven e.g., in U.S. Pat. No. 6,864,103 to Raymond et al., which isincorporated herein in its entirety for all purposes. It is within theability of one of skill in the art to select and prepare a probe thatincludes a complex of the invention, and which is suitable for aselected assay system. In an exemplary embodiment, the luminescent probemolecule is used to detect the presence or absence of an analyte in asample.

Thus, in a second aspect, the invention provides mixtures that contain aluminescent complex of the invention and an analyte.

In a third aspect, the invention provides a method of detecting thepresence or absence of an analyte in a sample. The method comprises (a)contacting the sample and a composition including a complex of theinvention; (b) exciting said complex; and (c) detecting luminescencefrom the complex.

In a fourth aspect, the invention provides a method of detecting thepresence or absence of an analyte in a sample. The method comprises (a)contacting the sample and a composition including a complex of theinvention, and a luminescence modifying group, wherein energy can betransferred between the complex and the luminescence modifying groupwhen the complex is excited, and wherein the complex and theluminescence modifying group can be part of the same molecule or be partof different molecules; and (b) exciting said complex; and (c)determining the luminescent property of the sample, wherein the presenceor absence of the analyte is indicated by the luminescent property ofthe sample. In one example, the presence or absence of the analyteresults in a change of the luminescent property of the sample.

In an exemplary embodiment, the analyte is detected using a competitionassay format. For example, the analyte, if present in the sample,displaces a targeting moiety of a complex of the invention from abinding site located on a recognition molecule, by binding to thebinding site.

Hence, in another aspect, the invention provides a kit including arecognition molecule and a complex of the invention. Exemplaryrecognition molecules include biomolecules, such as whole cells,cell-membrane preparations, antibodies, antibody fragments, proteins(e.g., cell-surface receptors, such as G-protein coupled receptors),protein domains, peptides, nucleic acids and the like. Alternatively thekit may contain a lanthanide ion and an organic ligand, which form aluminescent complex when contacted with each other.

Analytes

The compounds, complexes and methods of the invention can be used todetect any analyte or class of analytes in any sample. A sample maycontain e.g., a biological fluid or tissue. Other samples can e.g.,include solutions of synthetic molecules or extracts from a plant ormicroorganism (e.g., for drug screening efforts). Exemplary analytes arepharmaceutical drugs, drugs of abuse, synthetic small molecules,biological marker compounds, hormones, infectious agents, toxins,antibodies, proteins, lipids, organic and inorganic ions, carbohydratesand the like. (see e.g., U.S. Pat. No. 6,864,103 to Raymond et al. foradditional examples of analytes).

Synthesis

The following section and the Examples appended hereto set forthexemplary synthetic routes to compounds of the invention.

1-Hydroxy-2-pyridinone (1,2-HOPO) Complexes

Useful 1,2-HOPO ligands of the invention and their metal chelates may besynthesized using art recognized methods. In one example, the ligandsare synthesized utilizing a reactive 1,2-HOPO intermediate prepared fromthe corresponding acid as described, e.g., in Appendix B, which isincorporated into this application in its entirety.

Once the ligand is formed and purified, the metal complex is synthesizedby any of a wide range of art-recognized methods, including, forexample, by incubating a salt of the ligand with a metal salt, such as alanthanide salt (e.g., lanthanide trihalide, lanthanide triacetate). Thereaction of the ligand with the metal ion is carried out either beforeor after coupling the ligand to a targeting moiety in order to generatea complex of the invention.

For example, 1,2-HOPO derivatives in which the carboxylic acid isactivated as an acid halide and the N-hydroxyl group is protected can beused to prepare the organic ligands that form the complexes of theinvention.

An exemplary method of preparing a 1,2-HOPO chelator is outlined inScheme 1:

R¹ and R² represent members independently selected from the groupdescribed herein as aryl group substituents. The symbol R³ represents amember selected from the group of H, C₁-C₄ substituted or unsubstitutedalkyl, and substituted or unsubstituted aryl.

The method includes contacting compounds of structure 8 with aprotecting agent, thereby forming the protected compounds of structure9, in which P is a protecting group. Compounds according to structure 9are then contacted with an agent that converts the carboxylic acid tothe corresponding acid halide, thereby forming compounds of structure10, which are then contacted with HNR¹R² and subsequently deprotectedthereby forming the chelators according to structure 7.

An example of this method according to Scheme 1 is:

In an exemplary embodiment, the route from1-hydroxy-2(1H)pyridinone-6-carboxylic acid to the corresponding amideinvolves the steps:

In another exemplary route, the acid is activated withcarbonyldiimidazole:

In a presently preferred embodiment, the acid halide is an acidchloride. A presently preferred agent for converting the carboxylic acidto the halide is oxalyl chloride. Other acid halides and agents forconverting the carboxylic acid to those halides will be apparent tothose of skill in the art. See, for example, Wade, COMPENDIUM OF ORGANICSYNTHETIC METHODS, John Wiley and Sons, New York, 1984; and March,ADVANCED ORGANIC CHEMISTRY, 4th Edition, Wiley-Interscience, New York.

The protected 1,2-HOPO acid 9 can also be activated by forming variousactivated esters or amides. An exemplary reaction sequence is shownbelow in Scheme 2:

Benzyl protected 1,2-HOPO-6-carboxylic acid (1,2-HOPOBn acid) is aversatile compound for synthesizing 1,2-HOPO ligands. It can beconverted to various activated intermediates and then coupled to avariety of amines, sulfhydryls, alcohols and other nucleophilic groups.For example, 1,2-HOPO-6-carboxylic acid reacts with 2-mercaptothiazolinein the presence of DCC (dicyclohexyl carbodiimide) and DMAP(1,4-Dimethylaminopyridine) to give 1,2-HOPO thiazolide, whichselectively reacts with aliphatic primary amines, like its 3,2-HOPOanalogue, 3,2-HOPO-thiazolide. The protected HOPO-acid can also beconverted to the corresponding N-hydroxysuccinimide or other activatedesters and coupled to various backbones that include nucleophilicmoieties. In most cases, the active esters are not isolated, but arecoupled with amines or other nucleophilic moieties in situ.

Protecting agents and protecting groups useful in practicing the presentinvention are generally those known in the art to be of use inprotecting hydroxyl moieties (see, for example, Greene, PROTECTIVEGROUPS IN ORGANIC SYNTHESIS, 2nd Edition, Wiley-Interscience, 1991). Apresently preferred protecting group is the benzyl group. Preferredprotecting agents include, but are not limited to, benzyl halides,benzyl sulfonates, and benzyl triflates.

The chelating agent 1,2HOIQO is prepared and attached to an exemplaryscaffold by the scheme set forth below:

As will be apparent to those of skill in the art, if the synthesis isinitiated with a starting material functionalized on the phenyl ring orthe heterocycle, a similarly functionalized chelating moiety willresult. The scaffold set forth above is purely exemplary and it isunderstood that any of the scaffolds set forth herein, or art recognizedscaffolds are equally applicable.

Any nucleophilic species that reacts with the material according tostructure 10 is useful in practicing the present invention. In apreferred embodiment, the nucleophilic species is an amine, NR¹⁷R¹⁸. Ina further preferred embodiment, NR¹⁷R¹⁸ is a polyamine Preferredpolyamines include 1,3-diaminopropane, spermidine, and spermineRepresentative amine species to which compound 10 can be conjugatedinclude, but are not limited to, those set forth in U.S. Pat. No.4,698,431, U.S. Pat. No. 5,624,901 and U.S. Pat. No. 5,892,029, thedisclosures of which are incorporated herein by reference.

An exemplary synthetic route for the synthesis of octadentate,tetrapodal 1,2-HOPO ligands is outlined in Schemes 3 to 5:

In Scheme 3, H(2,2)-, H(3,2)- and H(4,2)-1,2-HOPO ligands aresynthesized via an aziridine intermediate, which is opened using theappropriate diamine, wherein the integer n is selected from 1 to 10,preferably 1 to 7.

Scheme 4 outlines the synthesis of H(5O,2)-1,2-HOPO.

Scheme 5 outlines the synthesis of H(8O2,2)-1,2-HOPO.

The carboxylic acid starting material according to structure 8 may beprepared by any method known in the art. In a preferred embodiment, thecarboxylic acid is prepared by a method that includes contacting atrifluoroacetic acid solution of a hydroxyl-containing compound having astructure according to structure 11:

with a mixture comprising acetic anhydride and hydrogen peroxide,thereby forming a precipitate of an N-hydroxyamide compound having astructure according to structure 9. Other starting materials for thepreparation of 8 include 6-chloro-picolinic acid and 6-bromo-picolinicacid.

Mixed ligands that include at least one 1,2-HOPO subunit in combinationwith another complexing moiety can also be prepare using art recognizedmethods.

Functionalization of 1-Hydroxy-2-Pyridinonate Chelating Agents

TAM moieties conveniently contain a second amide group, which can befunctionalized either prior to or following connection with the scaffoldmoiety (e.g., TREN in Scheme 6 or the octadentate scaffold H(2,2)).

A series of TREN-HOPO-TAM derivatives are synthesized using eitherroute. The choice of route may depend on the choice of amine RNH₂.

The use of benzyl (Bn) protecting groups on TAM is generally preferableto the methyl groups previously reported (Cohen, S. M. et al., Inorg.Chem. 2000, 39, 4339), since the deprotection conditions are lesssevere, making the method amenable to a greater range of primary amines(RNH₂).

Synthesis of Chelating Agents Containing PEG Functionalization

In another embodiment, the invention provides poly(ethylene glycol)(PEG) functionalized chelates. In an exemplary embodiment, the inventionprovides derivatives of TREN-1,2-HOPO-TAM 12. The PEG group increasesthe rather low solubility of the parent complexes.

Also included in the present invention is a method of preparing achelating agent having a polymeric backbone and at least onefunctionality to which a chelating ligand of the invention is bonded.Examples of suitable polymers include, but are not limited to,poly(styrene-divinylbenzene), agarose (manufactured by Bio-Rad Corp.,Richmond, Calif., under the name “Affi-Gel”), and polyacrylamide. Thoseof skill in the art will appreciate that the method of the invention isnot limited by the identity of the backbone species, and that numerousamine-, hydroxyl- and sulfhydryl-containing compounds are useful asbackbones in practicing the method of the invention.

Evaluation of Ligands and Complexes

The present invention generally utilizes art recognized methods tocharacterize the new ligands and their metal complexes. For example, thebasicity of the ligands can be assessed by determining the protonationconstants (pK_(a)'s) by potentiometric titrations.

Methods of determining stability constant measurements include, but arenot limited to those set forth in, Johnson, A. R. et al., Inorg. Chem.2000, 39: 2652-2660; and Cohen, S. M. et al., Inorg. Chem. 2000, 39:5747.

The Bjerrum method can be used for metal complex stability measurements(pH titrations of ligand and metal+ligand). Competition titrations withDTPA can be performed to determine the stability of very stablecomplexes where direct pH titration methods are inappropriate.Spectrophotometric techniques can be used to monitor metal-ligandcomplexation reactions which give rise to changes in the V is/UV spectrarelative to the parent metal and ligand species. Withdigitally-recording automated spectrophotometeric titrators, factoranalysis of the V is/UV spectra readily determined the species insolution, their individual spectra and the equilibrium constants, whichinterrelate them.

The emissive properties of Eu(III) and/or Tb(III), are used to reflectthe rates of emissive decay in distinct sites that the metal ionoccupies. Hence, luminescence titration of the Eu(III) and Tb(III)complexes of the ligands with HSA is a good method for determiningbiomolecule affinity (Feig, A. L. P. et al., Chem. & Biol. 1999, 6, 801;Chaudhuri, D. H. et al., Biochem. 1997, 36, 9674; Cronce, D. T. H. etal., Biochem. 1992, 31, 7963.

The following examples are provided to illustrate selected embodimentsof the invention and are not to be construed as limiting its scope.

EXAMPLES 2-Bromopyridine-6-carboxylic Acid

A 9.7-g (0.048-mol) portion of 6-bromopyridine-2-carboxylicacid wasadded to a solution of 125 mL of CF₃CO₂H and 18 mL of 30% H₂O₂ andheated to 80° C. for 6.5 h. The reaction mixture was concentrated to ca.25 mL by rotary evaporation and then added to 1 L of water. The productimmediately precipitated as a finely divided, white crystalline solid.It was isolated by filtration, washed with water, and dried in vacuum.This yielded 10.2 g (97%) of product, mp 180° C. dec.

¹H NMR (300 MHz, DMSO-d₆): δ 7.70 (t, 1H), 8.24 (dd, 1H), 8.29 (dd, 1H).Anal. Calcd for C₆H₄BrNO₃: C, 33.05; H, 1.85; Br, 36.65; N, 6.43. Found:C, 33.30; H, 1.88; Br. 36.37; N, 6.52.

1-Hydroxy-6-carboxy-2(1H)pyridinone

A 10.1-g (0.046 mol) portion of 2-bromopyridine-6-carboxylicAcid wasdissolved in 175 mL of a 10% aqueous KOH solution, and the resultingsolution was maintained at 80° C. overnight and then cooled in an icebath and treated with 85 mL of concentrated HCl. The white suspendedsolid was isolated by filtration, washed with dilute HCl followed bythree 15 mL portions of water, and then dried in vacuo yielding 6.21 g(86.4%), mp 216° C. dec.

An alternative route is described below: Acetic anhydride (100 ml) wasmixed with 30% hydrogen peroxide solution (25 ml) with cooling; themixture was stirred for 3 hr until a homogenous peracetic acid solutionformed. To a solution of 6-hydroxy-picolinic acid (Fluka, 25 g, 0.18mol) in a mixture of trifluoroacetic acid (150 mL) and glacial aceticacid (100 mL), the above peracetic acid solution was added slowly withstirring. (CAUTION! any solid particle in the mixture will causedvigorous oxygen release and lead to out of control of the reaction). Themixture stirred at room temperature for one 1 hr, and heated slowly to75° C. and kept at 80° C. (oil bath temperature) for 10 hr. Whiteprecipitate formed during this period, it was collected by filtration,washed with cold methanol, and dried in a vacuum oven, yield 20.5 g(0.132 mol, 73%). mp 176-177° C.

¹H NMR (300 MHz, DMSO-d₆): δ 6.634 (dd, J_(ortho)=7 Hz, J_(meta)=1.5 Hz,1H), 6.710 (dd, J_(ortho)=9.2 Hz, J_(meta)=1.5 Hz, 1H), 7.437 (dd,J_(ortho)=9, J_(meta)=7 Hz, 1H). ¹³C NMR (75 MHz, DMSO-d₆): δ 106.9,120.6, 135.0, 137.3, 157.4, 163.3. IR (KBr pellet) ν 1734 (br, C═O),1616 (m, C═O) cm⁻¹. Anal. Calcd (Found) for C₆H₅NO₄(F.W. 155.15): C,46.46 (46.31); H, 3.25 (3.45); N, 9.03 (9.12).

1-Benzyloxy-6-carboxy-2(1H)-pyridinone (1,2-HOPOBn acid)

1-Hydroxy-6-carboxy-2(1H)-pyridinone (15.5 g, 0.1 mol) and anhydrouspotassium carbonate (27.6 g, 0.2 mol) were mixed with benzyl chloride(15.2 g, 0.12 mol) in methanol (250 mL). The mixture was refluxed for 16h, filtered, and the filtrate evaporated to dryness. The residue wasdissolved in water (50 mL) and acidified with 6 N HCl to pH 2. The whiteprecipitate was isolated by filtration, washed with cold water, anddried in vacuum, to yield 22.3 g (91%) of1-Benzyloxy-6-carboxy-2(1H)-pyridinone, mp 176-177° C.

¹H NMR (300 MHz, CDCl₃): δ 5.269 (s, 2H), 6.546 (dd, J=1.6 Hz, J=6.7 Hz,1H), 6.726 (dd, J=1.6 Hz, J=9.2 Hz, 1H), 7.39-7.51 (m, 6H). ¹³C NMR (75MHz, DMSO-d₆): δ 77.9, 106.0, 124.1, 128.5, 129.1, 129.6, 133.8, 138.7,140.5, 157.7, 161.7. Anal. Calcd (Found) for C₁₃H₁₁NO₄: C, 63.66(63.75); H, 4.53 (4.55); N, 5.71 (5.52).

1,2-HOPOBn Acid Chloride

To a suspension of 1,2-HOPOBn acid (5.0 g, 20 mmol) in toluene orbenzene (50-70 mL), excess of oxalyl chloride (2.0 g) was added withstirring A lot of gas bubbles evolved and the suspension turned to beclear upon the addition of a drop of DMF as catalyst. The mixture wasthen warmed to 40° C. (oil bath temperature) for 4-6 hr, and the solventwas moved on a rotovap to leave pale yellow oil. The residual solventand oxallyl chloride were removed in a vacuum line (0.1 mm Hg) when theoil solidified as pale yellow crystalline solid, raw yield 5.0 g (95%).It is generally used directly for next step reaction without furtherpurification.

¹H NMR (300 MHz, CDCl₃): δ 5.32 (s, 2H), 6.88 (d, 1H), 6.94 (d, 1H),7.3-7.4 (m, 4H), 7.49 (m, 2H). ¹³C NMR (75 MHz, CDCl₃): δ 78.5, 112.3,128.4, 128.6, 129.4, 130.3, 132.7, 136.4, 140.2, 158.1, 158.8.

1-Benzyloxy-6-(2-thioxothiazolidin-1-yl)-carbonyl-2(1H)-pyridinone(1,2-HOPOBn-thiazolide)

To a solution of 1-benzyloxy-6-carboxy-2(1H)-pyridinone (4.90 g, 20mmol), 2-mercaptothiazoline (2.62 g, 22 mmol), and a catalytic amount of4-dimethyl-aminopyridine (DMAP) in dry THF (50 mL), was addedN,N′-dicyclohexylcarbodiimide (DCC) (4.6 g, 22 mmol). After stirringovernight, the dicyclohexylurea (DCU) solids are removed by filtrationthe yellow filtrate is removed by rotary evaporation to give a yellowsolid. Crystallization from isopropanol-methylene chloride gives thetitle compound (5.80 g, 83.7%) as a pale yellow powder, m.p.: 135-7° C.

¹H NMR (300 MHz, CDCl₃): δ 3.156 (t, J=7.4 Hz, 2H), 4.450 (t, J=7.4 Hz,2H), 5.321 (s, 2H), 6.176 (dd, J=1.6 Hz, J=6.8 Hz, 1H), 6.776 (dd, J=1.6Hz, J=9.2 Hz, 1H), 7.27-7.47 (m, 6H). ¹³C NMR (75 MHz, CDCl₃): δ 28.9,54.4, 78.9, 124.2, 128.6, 129.3, 129.8, 133.6, 137.8, 141.5, 158.1,159.6. Anal for C₁₇H₁₆N₂O₃S₂ Calcd. (Found): C, 55.47 (55.36); H, 4.07(4.17); N, 8.08 (7.83); S, 18.51 (18.41).

1-Hydroxy-6-N-octylcarboxamide-2(1H)-pyridinone (Octyl-1,2-HOPO)

Lipophilic bidentate 1,2-HOPO ligand with long aliphatic chains weresynthesized as raw models of lanthanide and actinide extractants. Thegeneral procedure for synthesizing such extractants is given below.

1,2-HOPO acid (1.00 g, 6.45 mmol) and 1,1′-carbonyldiimidazole (CDI)(1.05 g, 6.47 mmol) were stirred in dry DMF (40 mL) under N₂ for 2 hr.Octylamine (0.84 g, 6.46 mmol) was added to the above solution, and themixture stirred overnight. DMF was then removed by rotary evaporation,the residue taken up in dichloromethane (50 mL). It was extracted threetimes with 0.1 NaOH (3×25 mL) and the combined aqueous phase reduced involume to 20 mL by rotary evaporation. The concentrated solution wasacidified with 1 M HCl to pH 2, upon which a white precipitatedimmediately. It was collected by filtration, washed with cold water anddried in vacuo to give a beige solid (1.10 g, 63.1%).

¹H NMR (300 MHz, CDCl₃): δ 0.878 (t, 3H, CH₃), 1.27-1.39 (m, 10H, CH₂,1.653 (qint, 2H, CH₂), 3.49 (qint, 2H, CH₂), 7.06 (d, 1H, arom H), 7.45(d, 1H, arom H), 9.65 (s, 1H, NH). ¹³C NMR (300 MHz, CDCl₃): δ 14.1,22.6, 27.1, 29.2, 31.8, 113.9, 115.0, 133.0, 137.0, 156.4, 158.7.MS(FAB+): 266 (MH⁺). Anal. Calcd (Found) for C₁₄H₂₂N₂O₃: C, 63.13(62.71); H, 8.32 (8.47); N, 10.52 (10.63).

Preliminary extraction study indicated octyl-1,2-HOPO exhibits highspecificity extractant for Pu(IV) over a wide range of acidity and ionicstrength.

Carbostyril-124-1,2-HOPOBn (CS124-1,2-HOPOBn)

To a solution of carbostyril (0.174 g, 1 mmol) and dry triethylamine(0.4 ml, 4 mmol) in DMAA (20 mL) cooling with an ice bath, a solution ofraw 1,2-HOPOBn acid chloride (0.58 g, 2.2 mmol) in dry CH₂Cl₂ (35 mL)was added dropwisely with stirring. The mixture was heated at roomtemperature overnight, until TLC indicated the reaction was complete.The volatiles were removed under vacuo, and the residue was loaded on aflash silica column. Elution with 2-6% methanol in methylene chlorideallows the separation of the benzyl-protected precursorCS124-1,2-HOPOBn) (0.27 g, 67% based on CS-124) as a thick pale yellowoil.

¹H NMR (300 MHz, CDCl₃): δ 2.39 (s, 3H), 5.29 (s, 4H), 6.31 (s, 1H),6.55 (dd, 1H), 6.73 (dd, 1H), 7.25-7.45 (m, 5H), 7.55 (d, 1H), 7.69 (d,1H), 7.89 (d, 1H), 11.16 (s, 1H), 11.66 (s, 1H). ¹³C NMR (300 MHz,CDCl₃): δ 18.1, 79.2, 105.1, 106.1, 114.6, 117.2, 120.4, 123.8, 126.3,129.2, 129.8, 130.3, 134.4, 139.8, 140.2, 144.1, 148.4, 158.1, 159.6,162.7.

Carbostyril-124-1,2-HOPO(CS124-1,2-HOPO)

Since the 1,2-HOPO moiety is reductively sensitive to hydrogenation,most benzyl protected 1,2-HOPO ligands were deprotected under strongacidic conditions. CS124-1,2-HOPOBn (0.4 g, 1 mmol) was dissolved inconcentrated HCl (12 M)/glacial acetic acid (1:1, 20 mL), and stirred atroom temperature for 2 days. Removal of the solvent gives a beigeresidue, which was stirred with methanol to form a white slurry whichwas filtered to give CS124-1,2-HOPO (0.37 g, 93%) as a white powder.

¹H NMR (300 MHz, CDCl₃): δ 2.38 (s, 3H), 6.30 (s, 1H), 6.46 (dd, 1H),6.63 (dd, 1H), 7.36 (dd, 1H), 7.45 (dd, 1H), 7.68 (d, 1H), 7.88 (d, 1H),11.09 (s, 1H), 11.64 (s, 1H). ¹³C NMR (75 MHz, CDCl₃): δ 18.6, 104.0,105.5, 114.5, 116.7, 118.8, 120.2, 125.7, 137.7, 139.3, 140.2, 142.1,148.7, 157.6, 159.1, 162.1. MS (ES⁻): 310.1 (M⁻).

2,2-Dimethyl-3LI-1,2-HOPOBn

To a solution of 1,2-HOPOBn-thiazolide (1.22 g, 4 mmol) in dry methylenechloride (30 mL), was added neat 2,2-dimethyl-1,3-propanediamine (184mg, 1.8 mmol). The mixture was stirred overnight, solvent removed andloaded onto a flash silica column. Elution with 2-6% methanol inmethylene chloride allows the separation of the benzyl-protectedprecursor: 2,2-Dimethyl-3LI-1,2-HOPO-Bn (940 mg, 84.6%) as thick paleyellow oil.

¹H NMR (300 MHz, CDCl₃): δ 0.844 (s, 6H), 3.027 (d, br, 4H), 5.301 (s,4H), 6.307 (dd, 2H), 6.635 (dd, 2H), 7.246 (dd, 2H), 7.21-7.37 (m, 6H),7.43-7.46 (m, 4H), 7.650 (t, 2H, J=6.6 Hz). ¹³C NMR (75 MHz, CDCl₃): δ23.2, 36.5, 45.9, 53.2, 81.5, 104.7, 122.7, 128.0, 128.7, 129.3 133.0,137.9, 143.1, 158.1, 160.9.

2,2-Dimethyl-3LI-1,2-HOPO

2,2-Dimethyl-3LI-1,2-HOPO-Bn (557 mg, 1 mmol) was dissolved inconcentrated HCl (12 M)/glacial acetic acid (1:1, 20 mL), and wasstirred at room temperature for 2 days. Filtration followed by removalof the solvent gives a beige residue, which was washed with ether togive 2,2-Dimethyl-3LI-1,2-HOPO (412 mg, 92.1%) as a beige powder, m.p.115-117° C.

¹H NMR (300 MHz, DMSO-d₆): δ 0.892 (s, 6H), 3.114 (d, 4H), 6.314 (dd,2H), 6.573 (dd, 2H), 7.394 (dd, 2H), 8.730 (t, 2H, J=6.6 Hz). Anal forC₁₇H₁₈N₄O₆.3HCl.H₂O (485.34) Calcd. (Found): C, 42.07 (41.95); H, 5.40(5.67); N, 11.54 (11.29).

4LI-1,2-HOPOBn

The benzyl protected 4LI-1,2-HOPOBn was prepared following the procedurefor 2,2-dimethyl-3LI-1,2-HOPO-Bn, except 1,4-butanediamine (160 mg, 1.8mmol) was used instead of 2,2-dimethyl-1,3-propanediamine Separation andpurification of the benzyl-protected precursor was performed asdescribed above to give the desired product as pale yellow oil (77%based on amine).

¹H NMR (300 MHz, CDCl₃): δ 1.42 (s, br, 4H), 3.16 (d, br, 4H), 5.27 (s,4H), 6.35 (dd, 2H), 6.63 (dd, 2H), 6.86 (t, br, 2H), 7.24-7.46 (m, 12H).

4LI-1,2-HOPO

4LI-1,2-HOPOBn was deprotected following the procedure of2,2-dimethyl-3LI-1,2-HOPO, except 4LI-1,2-HOPOBn (543 mg, 1 mmol) wasused instead of 2,2-dimethyl-3LI-1,2-HOPOBn. Separation and purificationof the deprotected product are performed as described above to afford abeige solid (452 mg, 92.2%).

¹H NMR (300 MHz, DMSO-d₆): δ 1.52 (s, br, 4H), 3.21 (d, br, 4H), 6.26(dd, 2H), 6.55 (dd, 2H), 7.38 (dd, 2H), 8.74 (t, 2H, J=5.6 Hz). Anal forC₁₆H₁₈N₄O₆.3HCl.H₂O, Cacld. (Found): C, 39.23 (39.52); H, 3.73 (3.69);N, 11.43 (11.27).

5LI-1,2-HOPOBn

The benzyl protected 5LI-1,2-HOPOBn was prepared following the procedurefor 2,2-dimethyl-3LI-1,2-HOPO-Bn, except 1,5-pentanediamine (184 mg, 1.8mmol) was used instead of 2,2-dimethyl-1,3-propanediamine Separation andpurification of the protected precursor was performed as described aboveto give a pale yellow oil (0.9 g, 90% based on amine).

¹H NMR (300 MHz, CDCl₃): δ 1.18 (qin, 2H), 1.39 (qin, 4H), 3.17 (q, 4H),5.26 (s, 4H), 6.32 (dd, 2H), 6.62 (dd, 2H), 6.78 (t, 2H), 7.26-7.45 (m,12H). ¹³C NMR (75 MHz, CDCl₃): δ 23.4, 27.9, 39.3, 79.1, 105.9, 123.2,128.4, 129.2, 129.9 133.2, 138.5, 142.9, 158.5, 160.3.

5LI-1,2-HOPO

5LI-1,2-HOPO was deprotected following the procedure for2,2-dimethyl-3LI-1,2-HOPO, except 5LI-1,2-HOPOBn (557 mg, 1 mmol) wasused instead of 2,2-dimethyl-3LI-1,2-HOPOBn. Separation and purificationof the deprotected product was performed as described above to yield thedesired product as a beige solid (344 mg, 91%).

¹H NMR (300 MHz, DMSO-d₆): δ 1.35 (qin, 2H), 1.46 (qin, 4H), 3.18 (q,4H), 6.26 (dd, 2H), 6.55 (dd, 2H), 7.37 (dd, 2H), 8.73 (t, 2H, J=5.6).MS(FAB+): 377 (MH⁺). Anal for C₁₇H₂₀N₄O₆.2HCl.H₂O (467.32), Cacld.(Found): 43.69 (43.75), 5.17 (4.93), 11.98 (11.65).

C₅H₆N[Eu(5LI-1,2-HOPO)₂]

A solution of europium chloride hexahydrate (37 mg, 0.1 mmol) inmethanol (1 mL) was added to a solution of 5LI-1,2-HOPO.2HCl.H₂O (94 mg,0.20 mmol) in methanol (5 mL) while stirring. The mixture was refluxedfor 6 hr. under nitrogen, during which time the complex deposits as awhite precipitate. This solid was isolated by filtration, rinsed withcold methanol, and dried to give the pyridinium salt of title complex(80 mg, 82%) as a white solid.

Anal. For EuC₃₄H₃₆N₈O₁₂.C₅H₆N, Calcd. (Found): C, 47.76 (47.45); H, 4.32(4.22); N, 12.85 (12.67). MS (ES−): 900.1 (M⁻).

Crystals of Eu5LI-1,2-HOPO suitable for X-ray diffraction are preparedby vapor diffusion of ether into a wet methanol solution of the complexwith excess of dimethylamine. The ORTEP diagram and crystallographicdata have been mentioned in introduction section.

3-Oxapentane-1,5-diamine (5LIO-amine)

This amine was available from Aldrich as hydrochloride salt form at highcost. However the following modified literature procedure was quite easyto preparation good amount of the free amine.

A mixture of 34.7 g (0.5 mol) of NaN₃ and catalytical amount of KI (1 g)in 75 mL of H₂O and 6.8 g (0.02 mol) of cetylpyridinium chloride in 42.9g (0.3 mol) of 1,5-dichloro-3-oxapentan we refluxed and stirred for 20h. The reaction mixture was filtered, the organic phase of the filtrateseparated and the aqueous phase extracted with dichloromethane threetimes. The combined organic solution was extracted with 10% solution ofNa₂S₂O₃ to removed any iodine in the organic phase. The organic phasewas then loaded onto a flash silica gel plug to remove the pyridiniumsalt and residual water. Evaporation under vacuo at 25° C. affords 45 gof crude diazide. It was dissolved in 60 mL of 95% ethanol andhydrogenated at 25° C. (cooling with a water bath) and 50 atm in thepresence of 10% Pd/C (1.5 g). Filtration of the catalyst, evaporation ofthe solvent, and distillation gave 25 g (80%) of 5LIO-amine: bp 48-50°C. (1 torr)].

¹H NMR (300 MHz, CDCl₃): δ 1.33 (s, br, 4H), 2.83 (t, 4H), 3.45 (t, 4H).

5LIO-1,2-HOPOBn

To a solution of 1,2-HOPO(Bn)-thiazolide (644 mg, 2.1 mmol) in drymethylene chloride (20 mL), was added neat 5LIO-amine (104 mg, 1.0mmol). The mixture was stirred overnight, after which time the solventwas removed and the residue was loaded onto a flash silica column.Elution with 2-6% methanol in methylene chloride allowed for theseparation and isolation of the benzyl-protected 5LIO-1,2-HOPO(Bn) togive a pale yellow oil (447 mg, 85% based on amine).

¹H NMR (500 MHz, CDCl₃): δ 3.22 (s, 8H, CH₂), 5.24 (s, 4H, benzyl CH₂),6.26 (dd, J=7, 1.2 Hz, 2H, HOPO H), 6.31 (d, 2H, J=9.0 Hz, HOPO H), 7.24(dd, 2H, J=9.0, 2 Hz, ArH), 7.26-7.45 (m, 12H, ArH), 7.74 (s, br, 2H,amideH). ¹³C NMR (125 MHz, CDCl₃): δ 38.8, 68.1, 78.2, 104.7, 121.7,127.7, 128.3, 129.0, 132.9, 138.3, 143.2, 157.8, 160.0. MS(FAB+): 559.2(MH⁺).

5LIO-1,2-HOPO

5LIO-1,2-HOPOBn (558 mg, 1 mmol) was dissolved in concentrated HCl (12M)/glacial acetic acid (1:1, 20 mL), and was stirred at room temperaturefor 2 days. Filtration followed by removal of the solvent gave a beigeresidue, which was dissolved in a minimum amount of methanol and thenmixed with diethyl ether while stirring, 5LIO-1,2-HOPO precipitated, andwas collected by filtration and dried under vacuum at 80° C. affording awhite powder as product (340 mg, 90%).

¹H NMR (500 MHz, DMSO-d₆): δ 3.37 (q, 4H, J=6.0 Hz, CH₂), 3.52 (t, 4H,J=6.0 Hz, CH₂), 6.29 (dd, 2H, J=7.0, 1.5 Hz, HOPO H), 6.57 (dd, 2H,J=9.0, 2.0 Hz, HOPO H), 7.32 (dd, 2H, J=9.0, 2.0 Hz, HOPO H), 8.82 (t,2H, J=5.5 Hz, amide H). ¹³C NMR (300 MHz, CDCl₃): δ 39.2, 68.0, 108.4,120.2, 138.6, 139.7, 159.2, 161.7. MS(FAB+): 379 (MH⁺). Anal forC₁₆H₁₈N₄O₂ (378.34), Cacld. (Found): 50.79 (50.60), 4.80 (4.99), 14.80(14.50).

C₅H₆N [Eu-5LIO-1,2-HOPO].H₂O

A solution of europium chloride hexahydrate (37 mg, 0.1 mmol) inmethanol (1 mL) was added to a solution of 5LIO-1,2-HOPO (76 mg, 0.20mmol) in methanol (5 mL) while stirring. The clear solution becameturbid after 2 drops of dry pyridine was added. The mixture was refluxedfor 6 hr. under nitrogen, during which time the complex deposits as awhite precipitate. This solid was isolated by filtration, rinsed withcold methanol, and dried to give the pyridinium salt of title complex(63 mg, 63%) as a white solid.

Anal. for EuC₃₂H₃₂N₈O₁₄.C₅H₆N.H₂O, Calcd. (Found): C, 44.32 (44.15); H,4.02 (4.08); N, 12.57 (12.40). MS (ES−): 905.1 (M⁻).

Crystals of Eu5LIO-1,2-HOPO suitable for X-ray diffraction are preparedby vapor diffusion of ether into a methanol solution of the abovecomplex with 1 equivalent of tetramethylammonium hydroxide.

o-Phenylene-1,2-HOPOBn

To a mixture of o-phenylenediamine (0.11 g, 1 mmol) and 30% potassiumcarbonate solution (5 mL) in CH₂Cl₂ (20 mL) cooling with an ice bath, asolution of raw 1,2-HOPOBn acid chloride (0.64 g, 2.4 mmol) in dryCH₂Cl₂ (35 mL) was added dropwise within 1 hr with vigorous stirring.The mixture was warmed to room temperature with stirring, until TLCindicated the reaction was complete. The organic phase was separatedloaded on a flash silica column. Elution with 2-4% methanol in methylenechloride allows the separation of the benzyl-protected precursoro-phenylene-1,2-HOPOBn) (0.44 g, 79% based on the free amine) as a thickpale yellow oil which was solidified upon standing overnight.

¹H NMR (300 MHz, CDCl₃): δ 5.19 (s, 4H), 6.32 (dd, 2H), 7.13-7.30 (m,14H), 7.61 (m, 2H), 9.02 (s, 2H). ¹³C NMR (300 MHz, CDCl₃): δ 79.3,106.4, 123.5, 124.5, 126.4, 128.4, 128.7, 129.2, 132.7, 138.4, 142.6,158.4, 158.8. MS(FAB+): 562.2 (MH⁺).

o-Phenylene-1,2-HOPO

o-Phenylene-1,2-HOPOBn was deprotected under strong acidic condition asmentioned for CS124-1,2-HOPOBn, yield 90%.

¹H NMR (300 MHz, CDCl₃): δ 6.67 (m, 4H), 7.30 (dd, 2H), 7.47 (dd, 2H),7.69 (dd, 2H), 10.52 (s, 2H). ¹³C NMR (75 MHz, CDCl₃): δ 106.0, 120.0,125.5, 126.4, 130.2, 137.2, 141.5, 157.7, 159.1. MS(FAB+): 383.3 (MH⁺).Anal for C₁₈H1₄N₄O₆ (Mr. 382.33), Cacld. (Found): C, 56.55 (56.35); H,3.69 (3.57); N, 14.65 (14.48).

m-Phenylene-1,2-HOPOBn

The benzyl protected m-phenylene-1,2-HOPOBn was prepared following theprocedure for o-phenylene-1,2-HOPO-Bn, except m-phenylenediamine (160mg, 1.8 mmol) was used instead of o-phenylenediamine. Separation andpurification of the benzyl-protected precursor was performed asdescribed for that of o-phenylene-1,2-HOPOBn to give the desired productas pale yellow oil (95% based on amine).

¹H NMR (300 MHz, CDCl₃): δ 5.28 (s, 4H), 6.58 (d, 2H), 6.71 (d, 2H),7.15-7.30 (m, 14H), 7.44 (d, 2H), 7.92 (s, 1H), 9.26 (s, 2H). ¹³C NMR(300 MHz, CDCl₃): δ 79.0, 106.3, 112.0, 116.6, 122.9, 128.1, 128.8,129.3, 129.6, 132.6, 138.1, 138.3, 142.9, 158.0, 158.7. MS(FAB+): 562.2(MH⁺).

m-Phenylene-1,2-HOPO

1,3-Phenylene-Bis(1,2-HOPO) was prepared following the acidicdeprotection procedure of 2,2-dimethyl-3LI-1,2-HOPO as a beige solid(158 mg, 82.6%).

¹H NMR (300 MHz, DMSO-d₆): δ 6.43 (d, 2H), 6.61 (d, 2H), 7.34 (m, 1H),7.43 (m, 4H), 8.13 (s, 1H), 10.91 (s, 2H), 11.85 (s, br, 2H). MS(FAB+):383.3 (MH⁺). Anal for C₁₈H1₄N₄O₆ (Mr. 382.33), Cacld. (Found): C, 56.55(56.26); H, 3.69 (3.61); N, 14.65 (14.45).

2-Aminomethylaniline-1,2-HOPOBn (o-BnPhen-1,2-HOPOBn)

The benzyl protected o-BnPhen-1,2-HOPOBn was prepared following theprocedure for o-phenylene-1,2-HOPO-Bn, except 2-Aminomethyl-aniline (122mg, 1.0 mmol) was used instead of o-phenylenediamine Separation andpurification of the benzyl-protected precursor was performed asdescribed for that of o-phenylene-1,2-HOPOBn to give the desired productas pale yellow oil which was solidified upon standing (85% based onamine).

¹H NMR (500 MHz, CDCl₃): δ 4.32 (d, 2H), 4.79 (s, 2H), 5.37 (s, 2H),6.33 (dd, 1H), 6.40 (d, 2H), 6.69 (dd, 1H), 6.84 (d, 2H), 7.08 (m, 3H),7.19-7.31 (m, 6H), 7.38 (d, 1H), 7.44 (m, 3H), 8.01 (d, 1H), 8.26 (s,1H), 10.29 (s, 1H). ¹³C NMR (125 MHz, CDCl₃): δ 39.7, 78.3, 78.8, 104.7,106.4, 122.7, 123.0, 124.2, 125.9, 127.9, 128.3, 128.6, 129.3, 129.6,129.8, 130.8, 132.1, 132.9, 134.5, 137.7, 137.8, 141.3, 143.0, 157.9,158.1, 158.9, 160.4. MS(FAB+): 577 (MH⁺).

2-Aminomethylaniline-1,2-HOPO (o-BnPhen-1,2-HOPO)

o-BnPhen-1,2-HOPO) was prepared following the acidic deprotectionprocedure of CS124-1,2-HOPO. A beige solid was obtained as product,yield 86%.

¹H NMR (500 MHz, CDCl₃): δ 4.49 (s, 2H), 6.36 (dd, 1H), 6.58 (t, 2H),6.66 (d, 1H), 7.26 (t, 1H), 7.32 (t, 3H), 7.39-7.52 (m, 4H), 9.28 (t,1H), 10.62 (s, 1H). ¹³C NMR (125 MHz, CDCl₃): δ 104.0, 104.5, 119.7,125.5, 126.4, 127.5, 127.7, 132.6, 134.2, 137.2, 142.1, 157.5, 157.6,159.2, 160.8. MS(FAB+): 397.1 (MH⁺). Anal for C₁₉H₁₆N₄O₆ (Mr. 396.11),Cacld. (Found): C, 57.58 (57.29); H, 4.07 (4.01); N, 14.14 (13.82).

3-Aminomethylaniline-1,2-HOPOBn (m-BnPhen-1,2-HOPOBn)

The benzyl protected o-BnPhen-1,2-HOPOBn was prepared following theprocedure for o-phenylene-1,2-HOPO-Bn, except 3-Aminomethyl-aniline (122mg, 1.0 mmol) was used instead of o-phenylenediamine Separation andpurification of the benzyl-protected precursor was performed asdescribed for that of o-phenylene-1,2-HOPOBn to give the desired productas pale yellow oil which was solidified upon standing (87% based onamine).

¹H NMR (300 MHz, CDCl₃): δ 4.43 (d, 2H), 5.20 (s, 2H), 6.43 (dd, 2H),6.52 (m, 2H), 7.04 (d, 1H), 7.10-7.31 (m, 13H), 7.53 (s, br, 3H), 9.50(s, 1H). ¹³C NMR (125 MHz, CDCl₃): δ 43.0, 78.7, 105.7, 118.9, 122.7,123.6, 128.0, 128.7, 128.8, 128.9, 129.3, 129.6, 132.7, 137.7, 138.0,138.2, 142.6, 142.8, 158.0, 158.3, 160.1. MS(FAB+): 577 (MH⁺).

3-Aminomethylaniline-1,2-HOPO (m-BnPhen-1,2-HOPO)

m-BnPhen-1,2-HOPO) was prepared following the acidic deprotectionprocedure of CS124-1,2-HOPO. A beige solid was obtained as product,yield 86%.

¹H NMR (500 MHz, CDCl₃): δ 4.41 (s, 2H), 6.36 (d, 1H), 6.42 (d, 1H),6.60 (t, 2H), 7.10 (d, 1H), 7.32 (t, 1H), 7.32 (t, 3H), 7.39-7.47 (m,2H), 7.56 (d, 1H), 7.47 (s, 1H), 9.34 (t, 1H), 10.83 (s, 1H). ¹³C NMR(125 MHz, CDCl₃): δ 42.4, 103.6, 103.9, 118.3, 119.6, 119.9, 123.2,129.0, 137.4, 137.6, 138.4, 139.5, 142.2, 142.3, 157.5, 157.6, 158.7,160.5. MS(FAB+): 397.1 (MH⁺). Anal for C₁₉H₁₆N₄O₆ (Mr. 396.35), Cacld.(Found): C, 57.58 (57.36); H, 4.07 (4.02); N, 14.14 (13.93).

o-Aminomethyl-benzylamine-1,2-HOPOBn (o-diBnPhen-1,2-HOPOBn)

The benzyl protected o-diBnPhen-1,2-HOPOBn was prepared following theprocedure for o-phenylene-1,2-HOPO-Bn, except 2-Aminomethylbenzylaminewas used instead of o-phenylenediamine Separation and purification ofthe benzyl-protected precursor was performed as described for that ofo-phenylene-1,2-HOPOBn to give the desired product as pale yellow oilwhich was solidified upon standing (83% based on amine).

¹H NMR (500 MHz, CDCl₃): δ 4.44 (d, 4H), 5.08 (s, 4H), 6.19 (m, 4H),7.04 (dd, 2H), 7.10-7.15 (m, 2H), 720-7.40 (m, 12H), 7.83 (d, 2H). ¹³CNMR (125 MHz, CDCl₃): δ 40.5, 78.5, 105.3, 122.5, 127.8, 128.0, 128.7,129.4, 132.8, 135.0, 142.5, 158.0, 159.9. MS(FAB+): 591 (MH⁺).

o-Aminomethyl-benzylamine-1,2-HOPO (o-diBnPhen-1,2-HOPO)

o-diBnPhen-1,2-HOPO was prepared following the acidic deprotectionprocedure of CS124-1,2-HOPO. A beige solid was obtained as product,yield 90%. ¹H NMR (500 MHz, DMSO-d₆): δ 4.50 (s, 2H), 6.35 (dd, 2H),6.58 (dd, 2H), 6.66 (d, 1H), 7.26 (dd, 2H), 7.38 (m, 4H), 9.26 (t, 2H).¹³C NMR (125 MHz, CDCl₃): δ 103.9, 119.6, 127.3, 127.9, 135.9, 137.4,142.3, 157.6, 160.5. MS(FAB+): 397.1 (MH⁺). Anal for C₁₉H₁₆N₄O₆. 0.7 H₂O(Mr. 422.73), Cacld. (Found): C, 56.82 (57.02); H, 4.62 (4.59); N, 13.25(12.88).

TREN-1,2-HOPOBn

The benzyl protected TREN-1,2-HOPOBn was prepared following theprocedure for 2,2-dimethyl-3LI-1,2-HOPO-Bn, excepttris(2-aminoethyl)amine (TREN) was used instead of2,2-dimethyl-1,3-propanediamine Separation and purification of thebenzyl-protected precursor are performed as described above to give paleyellow oil (89% based on amine).

¹H NMR (300 MHz, CDCl₃): δ 2.329 (s, br, 6H), 2.992 (d, br, 4H), 5.234(s, 4H), 6.086 (dd, 6H), 6.365 (dd, 6H), 6.785 (t, 6H), 7.131 (dd, 6H)7.27-7.35 (m, 12H). ¹³C NMR (300 MHz, CDCl₃): δ 37.5, 52.9, 79.0, 105.0,122.8, 128.3, 129.0, 129.6 133.2, 138.4, 142.9, 158.1, 160.4.

TREN-1,2-HOPO

TREN-1,2-HOPO was prepared following the procedure for2,2-dimethyl-3LI-1,2-HOPO, except TREN-1,2-HOPOBn (827 mg, 1 mmol) wasused instead 2,2-dimethyl-3LI-1,2-HOPOBn. Separation and purification ofthe deprotected product was performed as described above affording abeige solid (502 mg, 90.1%).

¹H NMR (300 MHz, DMSO-d₆): δ 1.35 (qin, 2H), 1.47 (qin, 4H), 3.18 (q,4H), 6.26 (dd, 2H), 6.55 (dd, 2H), 7.37 (dd, 2H), 8.73 (t, 2H, J=5.6Hz). MS(FAB+): 558 (MH⁺). Anal for C₂₄H₂₂N₂O₉.HCl.H₂O, Cacld. (Found):47.10 (47.34), 4.94 (4.79), 16.02 (15.95).

Europium Complex with TREN-1,2-HOPO

To a solution of TREN-1,2-HOPO (61 mg, 0.10 mmol) in methanol (10 mL),was added a solution of europium chloride hexahydrate (36 mg, 0.1 mmol)in methanol (10 mL) while stirring. The clear solution becomes turbidafter 2 drops of dry pyridine are added. The mixture was refluxedovernight under nitrogen, during which time the complex deposits as awhite precipitate. This was filtered, rinsed with cold methanol, anddried to give the title complex (63 mg, 89%) as a white solid. Anal. forEuC₂₄H₂₄N₂O₉.H₂O, Calcd. (Found): C, 39.79 (40.01); H, 3.62 (3.47); N,13.53 (13.26).

Crystals of this compound suitable for X-ray diffraction are prepared byvapor diffusion of ether into a DMF solution. The chemical formula wasEu (C₂₄H₂₄N₇O₉.C₃H₇NO)₂2C₃H₇NOC₄H₁₀O. The ORTEP diagram andcrystallographic data and parameters for Eu-TREN-1,2-HOPO are given inintroduction section.

1,3,5-Tris(bromomethyl)-2,4,6-trimethoxybenzene (MeOMEtribromide)

To a solution of 1,3,5-trimethoxybenzene (5.0 g, 30 mmol) andparaformaldehyde (3.0 g, 99 mmol) in 10 mL of acetic acid was added 22mL of hydrogen bromide (30 wt % in HOAc). The mixture was heated at60-70° C. in a round bottom flask equipped with a condenser cooled withice water for 3 hrs. The mixture then was poured in 100 mL of water. Theprecipitate was filtered and dried. Flash chromatography usinghexane/ethyl acetate (20/1) as the eluent gave the product as whitepowder. Yield, 1.7 g (13%); mp 126° C. ¹H NMR (300 MHz, CDCl₃) δ 4.14(s, 9H), 4.60 (s, 6H).

1,3,5-Tris-azidomethyl-2,4,6-trimethoxy-benzene (MeOMEtriazide)

The MeOME-triazide was prepared in high yield from the correspondingtetrabromide by nucleophilic substitution with azide anion. The triazidewas handled with great care due to the high N:C ratio of this compound.In a typical preparation, MeOMEtribromide (0.9 g, 2 mmol) was mixed withexcess of sodium azide (1.0 g, 15 mmol) in dry DMF (20 mL). The mixturewas stirred at 40° C. overnight, the solvent was removed under reducedpressure at room temperature and the oily residue solidified afterstirring with cold water. It was then washed thoroughly with water andair dried. Yield 0.60 g (90%).

¹H NMR (500 MHz, CDCl₃) δ 3.92 (s, 9H, methoxy CH₃), 4.45 (s, 6H,ArCH₂). ¹³C NMR (125 MHz, CDCl₃) δ 44.1, 63.2, 119.8, 160.3.

1,3,5-Bis-aminomethyl-2,4,6-trimethoxy-benzylamine (MeOMEtriaamine)

To a solution of MeOMEtriazide (0.6 g, 2 mmol) in methanol (20 mL) wasadded palladium on carbon (10%) catalyst (50 mg). The mixture washydrogenated at room temperature in a Parr bomb at 500 psi overnight.The catalyst was then removed by filtration (fine glass frit) and thefiltrate was evaporated under reduced pressure, yield 0.41 g (90%). TheMeOMEtriaamine was directly used for the next amidation reaction.

¹H NMR (500 MHz, CDCl₃) δ 1.70 (s, 6H, ArCH₂), 3.81 (s, 9H, methoxy CH).¹³C NMR (125 MHz, CDCl₃) δ 35.4, 61.7, 126.1, 156.4.

MeOME-1,HOPOBn

To a mixture of o-MeOMEtriaamine (0.13 g, 0.5 mmol) and 30% potassiumcarbonate solution (5 mL) in CH₂Cl₂ (20 mL) cooling with an ice bath, asolution of raw 1,2-HOPOBn acid chloride (form 0.5 g of 1,2-HOPOBn avid,2 mmol) in dry CH₂Cl₂ (15 mL) was added dropwise within 1 hr withvigorous stirring. The mixture was warmed to room temperature withstirring, until TLC indicated the reaction was complete. The organicphase was separated loaded on a flash silica column. Elution with 2-5%methanol in methylene chloride allows the separation of thebenzyl-protected precursor o-phenylene-1,2-HOPOBn) (0.34 g, 74% based onthe free amine) as a thick pale yellow oil which was solidified uponstanding overnight.

¹H NMR (300 MHz, CDCl₃): δ 3.61 (s, 9H, CH₃), 4.57 (d, 6H, ArCH₂), 5.25(s, 6H), 6.40 (dd, 3H), 6.74 (dd, 3H), 6.95 (t, 3H, amide H), 7.20-7.36(m, 15H), 7.38 (d, 3H). MS(FAB+): 937 (MH⁺).

MeOME-1,2-HOPO

MeOME-1,2-HOPO was prepared following the acidic deprotection procedureof 2,2-dimethyl-3LI-1,2-HOPO as a beige solid, yield 83%.

¹H NMR (500 MHz, DMSO-d₆): δ 3.80 (s, 9H), 6.49 (d, 6H, ArCH₂), 6.38 (d,3H), 6.59 (dd, 3H), 7.37 (dd, 3H), 9.06 (t, 3H, amideH). ¹³C NMR (125MHz, DMSO-d₆) δ 33.5, 62.3, 105.1, 118.9, 120.5, 136.6, 141.5, 157.3,159.1, 159.8. MS(FAB+): 667 (MH⁺). Anal for C₃₀H₃₀N₆O₁₂.H₂O (Mr.684.606), Cacld. (Found): C, 52.63 (52.66); H, 4.71 (4.64); N, 12.27(12.42).

H(2,2)-1,2-HOPOBn

The benzyl protected H(2,2)-1,2-HOPOBn was prepared following theprocedure for 2,2-dimethyl-3LI-1,2-HOPOBn, except H(2,2) amine (orPENTEN, 198 mg, 0.9 mmol) was used instead of2,2-dimethyl-1,3-propanediamine Separation and purification of thebenzyl-protected precursor was performed as described above affording apale yellow oil (893 mg, 87% based on amine).

¹H NMR (300 MHz, CDCl₃): δ 1.77 (s, 2H), 2.20 (t, 8H), 3.02 (d, br, 8H),5.28 (s, 8H), 6.15 (dd, 4H), 6.59 (dd, 4H), 7.21 (dd, 4H), 7.30-7.34 (m,20H), 7.47-7.51 (m, 8H). ¹³C NMR (300 MHz, CDCl₃): δ 37.2, 51.8, 52.6,79.0, 105.0, 123.1, 128.3, 129.2, 130.0 133.2, 138.1, 142.8, 158.2,160.5.

H(2,2)-1,2-HOPO

H(2,2)-1,2-HOPO was prepared following the procedure for2,2-dimethyl-3LI-1,2-HOPO, except H(2,2)-1,2-HOPOBn (856 mg, 0.75 mmol)was used instead of 2,2-dimethyl-3LI-1,2-HOPOBn. Separation andpurification of the deprotected product was performed as described aboveyield a beige solid (529 mg, 81%).

¹H NMR (300 MHz, DMSO-d₆): δ 3.15 (s, br, 8H), 3.55 (s, br, 4H), 3.62(s, br, 8H), 6.42 (d, 2H), 6.59 (dd, 2H), 7.40 (dd, 2H), 9.05 (t, 2H,J=5.6 Hz). Anal for C₃₄H₄₀N₁₀O₁₂.2HCl.H₂O, Cacld. (Found): C, 46.84(46.75); H, 5.08 (5.10); N, 16.07 (16.05).

H(3,2)-1,2-HOPOBn

The benzyl protected H(3,2)-1,2-HOPOBn was prepared following theprocedure for H(2,2)-1,2-HOPOBn, exceptN,N,N′,N′-Tetrakis-(2-amino-ethyl)-propane-1,3-diamine, (H(3,2) amine220 mg, 0.9 mmol) was used instead of H(2,2)-amine. Separation andpurification of the benzyl-protected precursor was performed asdescribed above affording a pale yellow oil (0.73 g, 71% based onamine).

¹H NMR (500 MHz, CDCl₃): δ 1.03 (s, 2H), 1.87 (s, 4H), 2.13 (s, 8H),3.08 (s, br, 8H), 5.22 (s, 8H), 6.15 (d, 4H), 6.52 (d, 4H), 7.15 (t,4H), 7.30-7.34 (m, 12H), 7.44 (d, 8H), 7.49 (s, 4H). ¹³C NMR (125 MHz,CDCl₃): δ 24.2, 37.3, 51.0, 52.3, 78.8, 105.0, 122.9, 128.1, 128.9,129.7, 133.1, 138.0, 142.8, 158.1, 160.4. MS(FAB+, DTT/DTE): 1155.6(MH⁺).

H(3,2)-1,2-HOPO

H(3,2)-1,2-HOPO was prepared following the strong acidic deprotectionprocedure for H(2,2)-1,2-HOPO, except H(2,2)-1,2-HOPOBn (0.87 g, 0.75mmol) was used instead of H(2,2)-1,2-HOPOBn. Separation and purificationof the deprotected product was performed as described above yield abeige solid (0.52 g, 87%).

¹H NMR (500 MHz, DMSO-d₆): δ 1.67 (s, br, 2H), 2.70-2.85 (m, 12H), 3.07(s, br, 4H), 5.97 (dd, 4H), 6.02 (dd, 4H), 6.67 (dd, 4H). ¹H NMR (500MHz, CD₃OD): δ 20.5, 36.3, 51.7, 54.7, 109.9, 121.5, 138.8, 140.7,160.3, 163.8. Anal for C₃₅H₄₂N₁₀O₁₂.2HCl.1.5H₂O (894.714), Cacld.(Found): C, 46.98 (47.19); H, 5.29 (5.22); N, 15.66 (15.55). MS (ES⁻,MeOH): 793 (M⁻).

H(4,2)-1,2-HOPOBn

The benzyl protected H(4,2)-1,2-HOPOBn was prepared following theprocedure for H(2,2)-1,2-HOPOBn, exceptN,N,N′,N′-Tetrakis-(2-amino-ethyl)-butane-1,4-diamine, (H(4,2) amine 234mg, 0.9 mmol) was used instead of H(2,2)-amine. Separation andpurification of the benzyl-protected precursor was performed asdescribed above affording a pale yellow oil (0.72 g, 68% based onamine).

¹H NMR (500 MHz, CDCl₃): δ 0.85 (s, 4H), 1.95 (s, 4H), 2.29 (s, 8H),3.15 (s, br, 8H), 5.24 (s, 8H), 6.18 (s, 4H), 6.50 (dd, 4H), 7.14 (m,4H), 7.30-7.34 (m, 12H), 7.43-7.50 (m, 12H). ¹³C NMR (125 MHz, CDCl₃): δ23.9, 37.4, 52.1, 53.0, 78.8, 105.0, 122.9, 128.1, 128.9, 129.7, 133.1,137.8, 142.9, 158.1, 160.3. MS(FAB+, DTT/DTE): 1169.5 (MH⁺).

H(4,2)-1,2-HOPO

H(4,2)-1,2-HOPO was prepared following the strong acidic deprotectionprocedure for H(2,2)-1,2-HOPO. Separation and purification of thedeprotected product was performed as described above yield a beige solid(0.42 g, 90%).

¹H NMR (500 MHz, DMSO-d₆): δ 1.81 (s, br, 4H), 3.15 (s, 4H), 3.25 (s,8H), 3.55 (s, 8H), 6.43 (d, 4H), 6.59 (d, 4H), 7.40 (dd, 4H), 9.13 (t,4H), 10.96 (s, br, 4H). ¹H NMR (100 MHz, CD₃OD): δ 22.1, 36.3, 49.8,54.3, 109.7, 121.7, 139.1, 140.9, 160.3, 163.7. Anal forC₃₆H₄₄N₁₀O₁₂.2HCl.2.5H₂O (926.76), Cacld. (Found): C, 46.66 (46.82); H,5.54 (5.23); N, 15.11 (14.89). MS (ES⁻, MeOH): 807.3 (M⁻).

H(5O,2)-CBZ

Several approaches were tried to synthesize theN,N,N′,N′-Tetrakis-(2-amino-ethyl)-3-oxapentane-1,5-diamine[H(5O,2)-amine].It was found that the reaction of 5LIO-amine with CBZ-aziridine providesclean H(5O,2)-CBZ.

5LIO-amine (0.21 g, 2 mmol) and CbZ-aziridine (1.77 g, 10 mmol) weremixed in ten-butanol (30 mL) at room temperature under N₂. The mixturewas stirred under a N₂ atmosphere at 80° C. for 16 hrs, when TLC showedthe completeness of the reaction. The volatile were removed under vacuumand the residue was dissolved in dichloromethane. The appropriatefractions of a gradient flash silica gel column (1-7% methanol indicholoromethane) were collected and evaporated to dryness to give apale beige thick oil, yield: 1.28 g, 79%.

¹H NMR (300 MHz, CDCl₃): δ 2.53 (s, br, 12H), 3.17 (s, br, 4H), 3.83 (s,br, 8H), 5.04 (s, 8H), 7.29 (s, br, 20H). ¹³C NMR (300 MHz, CDCl₃): δ38.8, 53.0, 53.6, 69.3, 128.0, 128.1, 128.4, 136.6, 156.4. MS(FAB+,DTT/DTE): 813.5 (MH⁺).

H(5O,2)-amine

H(5O,2)CBZ (0.83 g, 1 mmol) and 0.1 g of Pd/C catalyst (palladium, 10wt. & on activated carbon (Aldrich)) were combined in methanol (25 mL).The mixture was hydrogenated (500 psi pressure, room temperature)overnight in a Parr bomb. After removing the catalyst by filtration, andthe filtrate was evaporated to dryness to leave pale yellow oil asproduct, yield 0.23 g (84%).

¹H NMR (500 MHz, DMSO-d₆): δ: 0.84 (t, 4H), 0.90 (t, 8H), 1.10 (t, 8H),1.66 (t, 4H). ¹³C NMR (500 MHz, CDCl₃) δ: 38.6, 53.4, 53.9, 70.1.

H(5O,2)-1,2-HOPOBn

The benzyl protected H(5O,2)-1,2-HOPOBn was prepared following theprocedure for H(2,2)-1,2-HOPOBn, except H(5O,2) amine (140 mg, 0.5 mmol)was used instead of H(2,2)-amine Separation and purification wereperformed as described for H(2,2)-1,2-HOPOBn affording a pale yellow oil(0.42 g, 71% based on amine).

¹H NMR (300 MHz, CDCl₃): δ 2.14 (s, br, 4H), 2.32 (s, br, 8H), 2.83 (s,br, 4H), 3.06 (s, br, 8H), 5.15 (s, 8H), 6.05 (s, 4H), 6.34 (s, 4H),7.04 (s, 4H), 7.20 (s, br, 12H), 7.32 (s, br, 8H). 7.63 (s, br, 4H). ¹³CNMR (300 MHz, CDCl₃): δ 37.3, 52.0, 52.7, 78.8, 104.8, 122.9, 128.1,128.9, 129.7, 133.1, 138.0, 143.0, 158.1, 160.3. MS(FAB+, DTT/DTE):1185.6 (MH⁺).

H(5O,2)-1,2-HOPO

H(2,2)-1,2-HOPOBn was deprotected following the procedure forH(2,2)-1,2-HOPO. Separation and purification of the deprotected productwas performed as described above yield a beige solid (81%).

¹H NMR (500 MHz, DMSO-d₆): δ 3.40 (s, br, 8H), 3.52 (s, br, 4H), 3.70(s, br, 8H), 3.86 (s, br, 4H), 6.41 (d, 4H), 6.60 (d, 4H), 7.40 (dd,4H), 9.11 (t, 2H, J=5.6 Hz), 10.48 (s, 4H). MS(FAB+, DTT/DTE): 824.3(MH⁺). Anal for C₃₆H₄₄N₁₀O₁₃.2HCl.H₂O, Cacld. (Found): C, 47.22 (47.54);H, 5.28 (5.35); N, 15.30 (14.95).

H(8O2,2)-CBZ

H(8O2,2)-CBZ was prepared following the procedure for H(5O,2)CBZ, except2-[2-(2-Amino-ethoxy)-ethoxy]-ethylamine (0.15 g, 1 mmol) was usedinstead of 5LIO-amine Separation and purification of the deprotectedproduct was performed as described for H(5O,2)-amine yielding paleyellow oil, yield: 0.64 g, 74%.

¹H NMR (300 MHz, CDCl₃): δ 2.53 (s, br, 12H), 3.16 (s, br, 8H), 3.23 (s,br, 4H), 3.35 (s, br, 4H), 5.03 (s, 8H), 7.28 (s, br, 20H). ¹³C NMR (300MHz, CDCl₃): δ 38.8, 52.6, 53.6, 66.3, 69.2, 69.9, 127.8, 128.0, 128.3,136.6, 156.5. MS(FAB+, DTT/DTE): 857.5 (MH⁺).

H(8O2,2)-amine

H(8O,2)CBZ (0.86 g, 1 mmol) and 0.1 g of Pd/C catalyst (palladium, 10wt. & on activated carbon (Aldrich)) were combined in methanol (25 mL).The mixture was hydrogenated (500 psi pressure, room temperature)overnight in a Parr bomb. After removing the catalyst by filtration, andthe filtrate was evaporated to dryness to leave pale yellow oil asproduct, yield 0.27 g (85%).

¹H NMR (300 MHz, D₂O) δ 2.49 (t, 4H), 2.54 (t, 8H), 2.78 (t, 8H), 3.34(t, 4H), 3.40 (t, 4H). ¹³C NMR (500 MHz, CDCl₃) δ 36.9, 51.3, 51.7,68.1, 69.3. MS(FAB+): 321.3 (MH⁺).

H(8O2,2)-1,2-HOPOBn

The benzyl protected H(8O2,2)-1,2-HOPOBn was prepared following theprocedure for H(2,2)-1,2-HOPOBn, except H(8O2,2) amine (0.16 g, 0.5mmol) was used instead of H(2,2)-amine Separation and purification wereperformed as described for H(2,2)-1,2-HOPOBn affording a pale yellow oil(0.41 g, 68% based on amine).

¹H NMR (300 MHz, CDCl₃): δ 2.31 (s, br, 4H), 2.42 (s, br, 8H), 2.63 (s,br, 4H), 2.85 (s, br, 4H), 3.14 (s, br, 8H), 5.32 (s, 8H), 6.20 (d, 4H),6.48 (d, 4H), 7.08 (s, 4H), 7.34 (s, br, 16H), 7.50 (s, br, 8H). ¹³C NMR(300 MHz, CDCl₃): δ 37.4, 52.2, 53.0, 68.8, 69.0, 79.0, 104.9, 123.0,129.1, 130.1, 133.3, 138.2, 143.2, 158.2, 160.4. MS(FAB+, NBA): 1229.7(MH⁺).

H(8O2,2)-1,2-HOPO

H(8O2,2)-1,2-HOPOBn was deprotected following the procedure forH(2,2)-1,2-HOPO. Separation and purification of the deprotected productwas performed as described above yield a beige solid (81%).

¹H NMR (500 MHz, DMSO-d₆): δ 3.36 (s, br, 8H), 3.47 (s, br, 4H), 3.62(s, br, 4H), 3.67 (q, br, 8H), 3.85 (s, br, 4H), 6.43 (dd, 4H), 6.60(dd, 4H), 7.41 (dd, 4H), 9.11 (t, 2H, J=5.6 Hz), 10.56 (s, 4H). ¹³C NMR(125 MHz, CD₃OD): δ 36.4, 49.3, 55.0, 66.0, 71.5, 110.2, 121.0, 139.0,141.1, 159.9, 163.2. MS(FAB+, NBA): 869 (MH⁺). Anal forC₃₈H₄₈N₁₀O₁₄.2HCl.2.5H₂O (986.81), Cacld. (Found): C, 46.25 (46.69); H,5.62 (5.71); N, 14.19 (13.89).

BocLys-H(2,2)-1,2-HOPOBn

To a solution of lysH(2,2)-amine{[5-Amino-6-((2-amino-ethyl)-{2-[bis-(2-amino-ethyl)-amino]-ethyl}-amino)-hexyl]-carbamicacid tert-butyl ester} (200 mg, 0.5 mmol) in dichloromethane (20 mL) 2mL of 40% potassium carbonate solution was added. The mixture was cooledwith an ice bath and vigorously stirred. A solution of raw 1,2-HOPOBnacid chloride (form 0.75 g 1,2-HOPOBn acid, 3 mmol) in dichloromethane(20 mL) was added slowly via a teflon tube equipped with a glasscapillary tip over a period of 1 hr. The reaction mixture was allowed towarm to room temperature and stirred overnight. The mixture was thenwashed with 1 M HCL (20 mL), and saline (20 mL) successively and loadedonto a flash silica column. Elution with 2-8% methanol in methylenechloride allows the separation of the benzyl-protected precursorLysH(2,2)-1,2-HOPOBn as beige foam, yield 70%.

¹H NMR (300 MHz, DMSO-d₆): δ 1.15 (s, br, 4H), 1.41 (s, 9H, BocH),1.9-2.8 (m, 14H), 2.8-3.3 (m, 8H), 3.79 (s, br, 1H), 4.90-5.40 (m, 8H),6.03 (s, 1H), 6.17 (d, 3H), 6.53 (d, 1H), 6.60 (d, 3H), 6.94 (d, 1H),7.0-7.4 (m, 19H), 7.4-7.5 (m, 8H), 7.71 (s, 1H, NH). ¹³C NMR (125 MHz,CDCl₃): δ 22.8, 28.2, 29.3, 31.9, 37.4, 37.5, 39.8, 48.7, 51.5, 51.9,52.8, 53.3, 53.7, 59.0, 78.6, 79.0, 104.6, 105.0, 123/1, 128.3, 129.1,129.7, 129.9, 130.0, 133.2, 133.3, 137.9, 138.1, 142.9, 143.1, 155.9,158.1, 158.2160.5, 160.7. MS(FAB+, NBA): 1312 (MH⁺).

Lys-H(2,2)-1,2-HOPO

BocLysH(2,2)-1,2-HOPOBn was deprotected following the procedure forH(2,2)-1,2-HOPO. Separation and purification of the deprotected productwas performed as described above yield a beige solid (81%).

¹H NMR (300 MHz, DMSO-d₆): δ 1.2-1.7 (m, br, 6H), 2.74 (s, br, 3H), 3.05(s, br, 3H), 3.15 (s, br, 5H), 3.55 (s, br, 3H), 3.61 (s, br, 6H), 4.15(s, br, 1H), 6.30-6.45 (m, 4H), 6.60 (d, 4H), 7.39 (m, 5H), 7.88 (s, br,3H), 8.85 (s, br, 1H), 9.00 (s, br, 1H), 9.06 (s, br, 2H). MS(FAB+,NBA): 851 (MH⁺). Anal for C₃₈H₄₉N₁₁O₁₂. 2HCl.H₂O. 2CH₃OH, Cacld.(Found): C, 47.72 (47.60); H, 6.11 (6.17); N, 15.30 (15.34)

LysEtGlutar-H(2,2)-1,2-HOPOBn

To a cooled solution of BocLysH(2,2)-1,2-HOPOBn (260 mg, 0.2 mmol) in 2mL dichloromethane (with an ice bath) 2 mL of trifluoroacetic acid wasadded neatly. The mixture was stirred for 4 hrs then evaporated todryness at room temperature. TLC confirms the BOC group was deprotectedcompletely. The residue was dissolved in dry THF (20 mL), drytriethylamine (0.5 mL) was added while cooling with an ice bath. To thiscold mixture, excess of ethyl glutarate N-hydroxysuccinimide ester (100mg, 0.4 mmol) was added under nitrogen. The mixture was stirred for 4hrs and the volatiles were removed under vacuum. The residue wasdissolved in dichloromethane and loaded onto a flash silica column.Elution with 2-8% methanol in methylene chloride allows the separationof the benzyl-protected precursor LysEtGlutarH(2,2)-1,2-HOPOBn as beigefoam, yield 70%.

¹H NMR (300 MHz, DMSO-d₆): δ 1.09 (s, br, 4H), 1.20 (t, 3H), 1.25 (t,4H), 1.84 (t, 2H), 2.02 (m, 2H), 2.17 (t, 6H), 2.28 (t, 6H), 2.98-3.1(m, 8H), 3.78 (s, br, 1H), 4.05 (q, 2H), 5.10-5.40 (m, 8H), 6.03 (s,1H), 6.16 (d, 3H), 6.45 (s, 1H), 6.51 (d, 1H), 6.58 (d, 3H), 7.15 (dd,1H), 7.18-7.40 (m, 18H), 7.40-7.51 (m, 8H), 8.00 (s, 1H, NH). ¹³C NMR(125 MHz, CDCl₃): δ 14.4, 21.2, 23.2, 25.5, 28.9, 31.9, 33.7, 35.5,37.7, 38.2, 39.0, 46.0, 49.1, 50.4, 52.1, 53.2, 54.5, 59.9, 60.6, 79.4,105.1, 105.6, 123.3, 123.5, 128.8, 129.6, 130.3, 130.4, 130.6, 133.7,133.8, 138.7, 143.4, 143.7, 143.8, 158.7, 158.8, 161.0, 161.2, 161.5,173.0, 173.5. MS(FAB+, NBA): 1354 (MH⁺).

LysGlutar-H(2,2)-1,2-HOPO

The deprotection of LysEtGlutar-H(2,2)-1,2-HOPOBn was performed in twosteps. The first step was the saponification. The hydrolyzedLysGlutar-H(2,2)-1,2-HOPOBn was then deprotected under strong acidiccondition as mentioned for LysH(2,2)-1,2-HOPOBn.

To a cooled solution of LysEtGlutar-H(2,2)-1,2-HOPOBn (0.27 g, 0.2 mmol)in 5 mL methanol (with an ice bath) 2 mL of KOH solution (1 M) wasadded. The mixture was stirred for 4 hrs when TLC confirms thehydrolysis of ester was complete. The mixture was evaporated to drynessat room temperature and the residue was dissolved in water (10 mL). Thehydrolyzed LysGlutar-H(2,2)-1,2-HOPOBn was precipitated uponacidification with HCl (1 M), it was collected, rinse with cold waterand further deprotected under strong acidic condition as mentioned aboveyield a beige solid (71%). ¹H NMR (300 MHz, DMSO-d₆): δ 1.37 (s, br,4H), 1.67 (t, 7H), 1.84 (t, 2H), 2.03 (m, 2H), 2.17 (t, 6H), 2.28 (t,6H), 2.98-3.1 (m, 8H), 3.78 (s, br, 1H), 4.05 (q, 2H), 6.41 (m, 4H),6.60 (m, 4H), 7.39 (m, 4H), 7.78 (t, 1H), 8.83 (m, 1H), 8.80 (m, 1H),9.05 (t, 2H). MS(FAB+, NBA): 966.4 (MH⁺). Anal for C₄₃H₅₅N₁₁O₁₅.HCl.4H₂O(1074.48), Cacld. (Found): C, 48.07 (48.34); H, 6.00 (6.09); N, 14.34(14.00)

3,4,3-LI-1,2-HOPOBn

To a solution of spermine (1.01 g, 5 mmol) in dichloromethane (50 mL) 10mL of 40% potassium carbonate was added. The mixture was cooled with anice bath and vigorously stirred. A solution of raw 1,2-HOPOBn acidchloride (form 5.4 g 1,2-HOPOBn acid, 25 mmol) in dichloromethane (50mL) was added slowly via a Teflon tube equipped with a glass capillarytip over a period of 1 hr. The reaction mixture was allowed to warm toroom temperature and stirred overnight. The mixture was then washed with1 M NaOH (100 mL), 1 M HCL (100 mL), and saline (100 mL) successively.The organic phase was loaded onto a flash silica column. Elution with2-6% methanol in methylene chloride allows the separation of thebenzyl-protected precursor 3,4,3-LI-1,2-HOPOBn as white foam, yield 80%.

¹H NMR (400 MHz, DMSO-d₆): δ 0.4-1.8 (m, 16H), 2.8-3.6 (m, 24H), 4.8-5.1(m, 2H), 4.88-5.05 (m, 2H), 5.15-5.30 (m, 4H), 5.30-5.45 (m, 2H),6.00-6.46 (m, 4H), 6.55-6.70 (m, 4H), 7.25-7.55 (m, 24H), 8.72-8.95 (m,2H, NH). MS(FAB+): 1111.5 (MH⁺).

3,4,3-LI-1,2-HOPO

The precursor 3,4,3-LI-1,2-HOPOBn was deprotected with 1:1 HCl(37%)/glacial HOAc for 2 days. The deprotection time could be reduced tofew hours if elevated temperature (up to 50° C.) was used. All thevolatiles were removed in vacuo, the residue was dissolved in minimumamount of methanol and precipitated with ether. The product was filteredand dried under vacuum, yield 91%.

¹H NMR (400 MHz, DMSO-d₆): δ 0.4-1.7 (m, 16H), 2.8-3.6 (m, 24H),6.1-6.25 (m, 6H), 6.25-6.35 (m, 2H), 6.45-6.55 (m, 8H), 7.31-7.42 (m,4H), 8.822 (q, 1H). 8.912 (q, 1H). MS(FAB+): 751 (MH⁺). Anal forC₃₄H₃₈N₈O₁₂.H₂O.2HCl (841.68), Calcd. (found): C, 48.52 (48.16); H, 5.03(4.82); N, 13.31 (13.23).

Synthesis of 1,2-HOPO Functional Polystyrene resin

1,2-HOPO acid (700 mg) and CDI were stirred in DMF under nitrogen for 2hr. The dien Merrifield resin (Suzuki, T. M.; Yokoyama, T. Polyhedron1984, 3, 939-945) was added, and the suspension stirred for 4 days. Theresin was collected by filtration and washed with methanol (3×50 mL) andacetone (3×50 mL), then dried in vacuo at 70° C., yield 60%. The resinwas then treated with 10 mL concentrated sulfuric acid containingcatalytic amount of silver sulfate (50 mg) for 4 hr. The sulfonatedresin was collected by filtration, washed with anhydrous dioxane (3×50mL), methanol (3×50 mL), and water (4×50 mL) successively. The productwas then dried in vacuo at 70° C. for 4 hr. IR(KBr pellet) ν 1653 (s,C═O) cm⁻¹. Anal. Found: C, 80.15; H, 7.32, N, 5.39.

Synthesis of Functional Water Soluble Polymer Bearing 1,2-HOPO Units

To a solution of 1.7 g commercially available water soluble polyaminepolymer, PEI (average molecular weight=30 K Dalton) in dry DMF (50 mL),was added 3.46 g of 1,2-HOPOBn-thiazolide. The solution was stirred atroom temperature for 24 h. The solvent was removed and the residue wasdissolved in 50 mL of water containing 1 mL of glacial acetic acid. Thesolution was extracted with methylene chloride 3 times to remove thebyproducts and evaporated to dryness. The residue was dissolved in 20 mLof a 1:1 mixture of glacial acetic acid and hydrochloric acid (37%). Themixture was stirred at room temperature for 2 days, and evaporated todryness, Yield: 85% to 90%. Initial testing indicated this water-solublepolymer shows strong affinity towards lanthanide and actinides ions.

All publications and patent documents cited in this application areincorporated by reference in their entirety for all purposes to the sameextent as if each individual publication or patent document were soindividually denoted. By their citation of various references in thisdocument, Applicants do not admit any particular reference is “priorart” to their invention.

What is claimed is:
 1. A compound having the structure:

wherein R², R³, and R⁴ are members independently selected from H, anaryl group substituent, a linker to a scaffold moiety, and a linker to afunctional moiety; R⁷, R⁸, and R⁹ are members independently selectedfrom H, substituted or unsubstituted alkyl, substituted or unsubstitutedheteroalkyl, substituted or unsubstituted aryl, substituted orunsubstituted heteroaryl, substituted or unsubstituted heterocycloalkyl,halogen, CN, CF₃, —C(O)R¹⁷, —SO₂NR¹⁷R¹⁸, —NR¹⁷R¹⁸, —OR¹⁷, —S(O)₂R¹⁷,—COOR¹⁷, —S(O)₂OR¹⁷, —OC(O)R¹⁷, —C(O)NR¹⁷R¹⁸, —NR¹⁷C(O)R¹⁸, —NR¹⁷SO₂R¹⁸,—NO₂, a linker to a functional moiety, and a linker to a scaffoldmoiety, wherein at least two of R⁷, R⁸, and R⁹ are optionally joined toform a ring system which is a member selected from substituted orunsubstituted cycloalkyl, substituted or unsubstituted heterocycloalkyl,substituted or unsubstituted aryl, and substituted or unsubstitutedheteroaryl; R¹⁷ and R¹⁸ are each members independently selected from H,substituted or unsubstituted alkyl, substituted or unsubstitutedheteroalkyl, substituted or unsubstituted aryl, substituted orunsubstituted heteroaryl, substituted or unsubstituted heterocycloalkyl,a linker to a functional moiety, and a linker to a scaffold moiety; andR¹⁷ and R¹⁸, together with the atoms to which they are attached, areoptionally joined to form a 5- to 7-membered ring; A and B are membersindependently selected from carbon, nitrogen, sulfur, and oxygen; D is amember selected from carbon and nitrogen; wherein if A is oxygen orsulfur, R⁹ is not present; wherein if B is oxygen or sulfur, R⁷ is notpresent; Z is a member selected from substituted or unsubstituted alkyl,substituted or unsubstituted heteroalkyl, substituted or unsubstitutedaryl, substituted or unsubstituted heteroaryl, substituted orunsubstituted heterocycloalkyl, N, NR³⁰, O, S, and CR³¹R³², wherein R³⁰,R³¹, and R³² are members independently selected from H, substituted orunsubstituted alkyl, substituted or unsubstituted heteroalkyl,substituted or unsubstituted aryl, substituted or unsubstitutedheteroaryl, and substituted or unsubstituted heterocycloalkyl; Y¹ and Y²are linker moieties, which are members independently selected from—C(O), —C(O)NR⁵—, —C(O)O—, —C(O)S—, and —C(O)CR²⁰R²¹, wherein R⁵, R²⁰,and R²¹ are members independently selected from H, substituted orunsubstituted alkyl, substituted or unsubstituted heteroalkyl,substituted or unsubstituted aryl, substituted or unsubstitutedheteroaryl, substituted or unsubstituted heterocycloalkyl, and afunctional moiety; and L¹ and L² are linker groups, which are membersindependently selected from a bond, substituted or unsubstituted alkyl,substituted or unsubstituted heteroalkyl, substituted or unsubstitutedaryl, substituted or unsubstituted heteroaryl, and substituted orunsubstituted heterocycloalkyl; wherein at least one of Z, L¹, and L² issubstituted with a moiety having the structure:

wherein L³ is a linker group, which is a member selected from a bond,substituted or unsubstituted alkyl, substituted or unsubstitutedheteroalkyl, substituted or unsubstituted aryl, substituted orunsubstituted heteroaryl, and substituted or unsubstitutedheterocycloalkyl; O has the structure:

wherein Z² is a member selected from substituted or unsubstituted alkyl,substituted or unsubstituted heteroalkyl, substituted or unsubstitutedaryl, substituted or unsubstituted heteroaryl, substituted orunsubstituted heterocycloalkyl, N, NR³⁰, O, S, and CR³¹R³², Y³ and Y⁴are linker moieties, which are members independently selected from—C(O), —C(O)NR⁵—, —C(O)O—, —C(O)S—, and —C(O)CR²⁰R²¹, L⁴ and L⁵ arelinker groups, which are members independently selected from a bond,substituted or unsubstituted alkyl, substituted or unsubstitutedheteroalkyl, substituted or unsubstituted aryl, substituted orunsubstituted heteroaryl, and substituted or unsubstitutedheterocycloalkyl; and one of Z², L⁴, and L⁵ is linked to L³; whereinsaid compound is substituted with at least one functional moiety havingthe structure:

wherein L⁶ is a linker group, which is a member selected fromsubstituted or unsubstituted alkyl, substituted or unsubstitutedheteroalkyl, substituted or unsubstituted heterocycloalkyl, substitutedor unsubstituted aryl, and substituted or unsubstituted heteroaryl; andX¹ is a member selected from a reactive functional group and a targetingmoiety.
 2. The compound according to claim 1, wherein the scaffoldmoiety is a member selected from substituted or unsubstituted alkyl andsubstituted or unsubstituted heteroalkyl.
 3. The compound according toclaim 1, wherein at least one of Z, Y¹, Y², L¹, and L² is substitutedwith a functional moiety.
 4. The compound according to claim 1, whereinZ is O, and L and L² are each ethyl.
 5. The compound according to claim1, wherein said targeting moiety comprises a member selected from asmall-molecule ligand, a peptide, a protein, a fusion protein, anenzyme, an antibody, an antibody fragment, an antigen, a nucleic acid, acarbohydrate, a lipid, and a pharmacologically active molecule.
 6. Thecompound according to claim 1, wherein said reactive functional group isa member selected from —OH, —SH, —NH₂, —C(O)NHNH₂ (hydrazide),maleimide, activated ester, aldehyde, ketone, hydroxylamine, imidoester,isocyanate, isothiocyanate, sulfonylchloride, acylhalide, and —COOY,wherein Y is a member selected from H, a negative charge and a saltcounter-ion.
 7. The compound according to claim 1, wherein thefunctional moiety is a member selected from:

wherein X² is a member selected from OH, alkoxy,

wherein R²² is a member selected from H, substituted or unsubstitutedalkyl, and substituted or unsubstituted aryl; v is an integer from 1 to20; and w is an integer from 1 to 1,000.
 8. The compound according toclaim 1, wherein said functional moiety has the structure:

wherein, Z⁵ is a member selected from H, OR²³, SR²³, NHR²³, OCOR²⁴,OC(O)NHR²⁴, NHC(O)OR²³, OS(O)₂OR²³, and C(O)R²⁴; wherein R²³ is a memberselected from H, substituted or unsubstituted alkyl, and substituted orunsubstituted heteroalkyl; R²⁴ is a member selected from H, OR²⁵,NR²⁵NH₂, SH, C(O)R²⁵, NR²⁵H, substituted or unsubstituted alkyl, andsubstituted or unsubstituted heteroalkyl; wherein R²⁵ is a memberselected from H, substituted or unsubstituted alkyl, and substituted orunsubstituted alkyl; X³ is a member selected from O, S, and NR²⁶ whereinR²⁶ is a member selected from H, substituted or unsubstituted alkyl, andsubstituted or unsubstituted heteroalkyl; and j and k are membersindependently selected from the group consisting of integers from 1 to20.
 9. The compound according to claim 1, wherein said functional moietycomprises a polyether.
 10. The compound according to claim 9, whereinsaid polyether is a member selected from polyethylene glycol (PEG) andderivatives thereof.
 11. The compound according to claim 10, whereinsaid polyether has a molecular weight of about 50 to about 10,000daltons.
 12. The compound according to claim 1, having a structureselected from:


13. A complex comprising a compound according to claim 1 and a metalion.
 14. The complex according to claim 13, wherein said metal ion isselected from a lanthanide ion, an actinide ion, and a transition metalion.
 15. The complex according to claim 14, wherein said lanthanide ionis selected from La³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Er³⁺, Tm³⁺,Yb³⁺, and Lu³⁺.
 16. The complex according to claim 14, wherein saidactinide ion is selected from U⁶⁺, Np⁴⁺, Np⁵⁺, Pu⁴⁺, and Am³⁺.
 17. Thecomplex according to claim 14, wherein said transition metal ion isFe³⁺.
 18. The complex according to claim 13, wherein the metal is aradioactive isotope.